Merge pull request #45 from atlarge-research/refactor/decouple

Decouple simulation logic from OpenDC Compute

24 files changed, 2103 insertions, 32 deletions

diff --git a/simulator/opendc-simulator/build.gradle.kts b/simulator/opendc-simulator/build.gradle.kts
index a740dcf3..e69de29b 100644
--- a/simulator/opendc-simulator/build.gradle.kts
+++ b/simulator/opendc-simulator/build.gradle.kts
@@ -1,32 +0,0 @@
-/*
- * Copyright (c) 2020 AtLarge Research
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- */
-
-description = "Simulation-specific code for use in OpenDC"
-
-/* Build configuration */
-plugins {
-    `kotlin-library-convention`
-}
-
-dependencies {
-    api("org.jetbrains.kotlinx:kotlinx-coroutines-test:${Library.KOTLINX_COROUTINES}")
-}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/build.gradle.kts b/simulator/opendc-simulator/opendc-simulator-compute/build.gradle.kts
new file mode 100644
index 00000000..cd7e5706
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/build.gradle.kts
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+description = "Library for simulation of cloud computing components"
+
+plugins {
+    `kotlin-library-convention`
+}
+
+dependencies {
+    api(project(":opendc-simulator:opendc-simulator-core"))
+
+    testImplementation("org.junit.jupiter:junit-jupiter-api:${Library.JUNIT_JUPITER}")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:${Library.JUNIT_JUPITER}")
+    testImplementation("org.junit.platform:junit-platform-launcher:${Library.JUNIT_PLATFORM}")
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt
new file mode 100644
index 00000000..c6d5bdd1
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt
@@ -0,0 +1,281 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.intrinsics.startCoroutineCancellable
+import kotlinx.coroutines.selects.SelectClause0
+import kotlinx.coroutines.selects.SelectInstance
+import org.opendc.simulator.compute.workload.SimWorkload
+import java.lang.Runnable
+import java.time.Clock
+import kotlin.coroutines.ContinuationInterceptor
+import kotlin.math.ceil
+import kotlin.math.max
+import kotlin.math.min
+
+/**
+ * A simulated bare-metal machine that is able to run a single workload.
+ *
+ * A [SimBareMetalMachine] is a stateful object and you should be careful when operating this object concurrently. For
+ * example. the class expects only a single concurrent call to [run].
+ *
+ * @param coroutineScope The [CoroutineScope] to run the simulated workload in.
+ * @param clock The virtual clock to track the simulation time.
+ * @param model The machine model to simulate.
+ */
+@OptIn(ExperimentalCoroutinesApi::class, InternalCoroutinesApi::class)
+public class SimBareMetalMachine(
+    private val coroutineScope: CoroutineScope,
+    private val clock: Clock,
+    override val model: SimMachineModel
+) : SimMachine {
+    /**
+     * A [StateFlow] representing the CPU usage of the simulated machine.
+     */
+    override val usage: StateFlow<Double>
+        get() = usageState
+
+    /**
+     * The current active workload.
+     */
+    private var activeWorkload: SimWorkload? = null
+
+    /**
+     * Run the specified [SimWorkload] on this machine and suspend execution util the workload has finished.
+     */
+    override suspend fun run(workload: SimWorkload) {
+        require(activeWorkload == null) { "Run should not be called concurrently" }
+
+        try {
+            activeWorkload = workload
+            workload.run(ctx)
+        } finally {
+            activeWorkload = null
+        }
+    }
+
+    /**
+     * The execution context in which the workload runs.
+     */
+    private val ctx = object : SimExecutionContext {
+        override val machine: SimMachineModel
+            get() = this@SimBareMetalMachine.model
+
+        override val clock: Clock
+            get() = this@SimBareMetalMachine.clock
+
+        override fun onRun(
+            batch: Sequence<SimExecutionContext.Slice>,
+            triggerMode: SimExecutionContext.TriggerMode,
+            merge: (SimExecutionContext.Slice, SimExecutionContext.Slice) -> SimExecutionContext.Slice
+        ): SelectClause0 {
+            return object : SelectClause0 {
+                @InternalCoroutinesApi
+                override fun <R> registerSelectClause0(select: SelectInstance<R>, block: suspend () -> R) {
+                    // Do not reset the usage state: we will set it ourselves
+                    usageFlush?.dispose()
+                    usageFlush = null
+
+                    val queue = batch.iterator()
+                    var start = Long.MIN_VALUE
+                    var currentWork: SliceWork? = null
+                    var currentDisposable: DisposableHandle? = null
+
+                    fun schedule(slice: SimExecutionContext.Slice) {
+                        start = clock.millis()
+
+                        val isLastSlice = !queue.hasNext()
+                        val work = SliceWork(slice)
+                        val candidateDuration = when (triggerMode) {
+                            SimExecutionContext.TriggerMode.FIRST -> work.minExit
+                            SimExecutionContext.TriggerMode.LAST -> work.maxExit
+                            SimExecutionContext.TriggerMode.DEADLINE -> slice.deadline - start
+                        }
+
+                        // Check whether the deadline is exceeded during the run of the slice.
+                        val duration = min(candidateDuration, slice.deadline - start)
+
+                        val action = Runnable {
+                            currentWork = null
+
+                            // Flush all the work that was performed
+                            val hasFinished = work.stop(duration)
+
+                            if (!isLastSlice) {
+                                val candidateSlice = queue.next()
+                                val nextSlice =
+                                    // If our previous slice exceeds its deadline, merge it with the next candidate slice
+                                    if (hasFinished)
+                                        candidateSlice
+                                    else
+                                        merge(candidateSlice, slice)
+                                schedule(nextSlice)
+                            } else if (select.trySelect()) {
+                                block.startCoroutineCancellable(select.completion)
+                            }
+                        }
+
+                        // Schedule the flush after the entire slice has finished
+                        currentDisposable = delay.invokeOnTimeout(duration, action)
+
+                        // Start the slice work
+                        currentWork = work
+                        work.start()
+                    }
+
+                    // Schedule the first work
+                    if (queue.hasNext()) {
+                        schedule(queue.next())
+
+                        // A DisposableHandle to flush the work in case the call is cancelled
+                        val disposable = DisposableHandle {
+                            val end = clock.millis()
+                            val duration = end - start
+
+                            currentWork?.stop(duration)
+                            currentDisposable?.dispose()
+
+                            // Schedule reset the usage of the machine since the call is returning
+                            usageFlush = delay.invokeOnTimeout(1) {
+                                usageState.value = 0.0
+                                usageFlush = null
+                            }
+                        }
+
+                        select.disposeOnSelect(disposable)
+                    } else if (select.trySelect()) {
+                        // No work has been given: select immediately
+                        block.startCoroutineCancellable(select.completion)
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * The [MutableStateFlow] containing the load of the server.
+     */
+    private val usageState = MutableStateFlow(0.0)
+
+    /**
+     * A disposable to prevent resetting the usage state for subsequent calls to onRun.
+     */
+    private var usageFlush: DisposableHandle? = null
+
+    /**
+     * Cache the [Delay] instance for timing.
+     *
+     * XXX We need to cache this before the call to [onRun] since doing this in [onRun] is too heavy.
+     * XXX Note however that this is an ugly hack which may break in the future.
+     */
+    @OptIn(InternalCoroutinesApi::class)
+    private val delay = coroutineScope.coroutineContext[ContinuationInterceptor] as Delay
+
+    /**
+     * A slice to be processed.
+     */
+    private inner class SliceWork(val slice: SimExecutionContext.Slice) {
+        /**
+         * The duration after which the first processor finishes processing this slice.
+         */
+        val minExit: Long
+
+        /**
+         * The duration after which the last processor finishes processing this slice.
+         */
+        val maxExit: Long
+
+        /**
+         * A flag to indicate that the slice will exceed the deadline.
+         */
+        val exceedsDeadline: Boolean
+            get() = slice.deadline < maxExit
+
+        /**
+         * The total amount of CPU usage.
+         */
+        val totalUsage: Double
+
+        /**
+         * A flag to indicate that this slice is empty.
+         */
+        val isEmpty: Boolean
+
+        init {
+            var totalUsage = 0.0
+            var minExit = Long.MAX_VALUE
+            var maxExit = 0L
+            var nonEmpty = false
+
+            // Determine the duration of the first/last CPU to finish
+            for (i in 0 until min(model.cpus.size, slice.burst.size)) {
+                val cpu = model.cpus[i]
+                val usage = min(slice.limit[i], cpu.frequency)
+                val cpuDuration = ceil(slice.burst[i] / usage * 1000).toLong() // Convert from seconds to milliseconds
+
+                totalUsage += usage / cpu.frequency
+
+                if (cpuDuration != 0L) { // We only wait for processor cores with a non-zero burst
+                    minExit = min(minExit, cpuDuration)
+                    maxExit = max(maxExit, cpuDuration)
+                    nonEmpty = true
+                }
+            }
+
+            this.isEmpty = !nonEmpty
+            this.totalUsage = totalUsage
+            this.minExit = minExit
+            this.maxExit = maxExit
+        }
+
+        /**
+         * Indicate that the work on the slice has started.
+         */
+        fun start() {
+            usageState.value = totalUsage / model.cpus.size
+        }
+
+        /**
+         * Flush the work performed on the slice.
+         */
+        fun stop(duration: Long): Boolean {
+            var hasFinished = true
+
+            for (i in 0 until min(model.cpus.size, slice.burst.size)) {
+                val usage = min(slice.limit[i], model.cpus[i].frequency)
+                val granted = ceil(duration / 1000.0 * usage).toLong()
+                val res = max(0, slice.burst[i] - granted)
+                slice.burst[i] = res
+
+                if (res != 0L) {
+                    hasFinished = false
+                }
+            }
+
+            return hasFinished
+        }
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimExecutionContext.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimExecutionContext.kt
new file mode 100644
index 00000000..5801fcd5
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimExecutionContext.kt
@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.selects.SelectClause0
+import kotlinx.coroutines.selects.select
+import java.time.Clock
+
+/**
+ * A simulated execution context in which a bootable image runs. This interface represents the
+ * firmware interface between the running image (e.g. operating system) and the physical or virtual firmware on
+ * which the image runs.
+ */
+public interface SimExecutionContext {
+    /**
+     * The virtual clock tracking simulation time.
+     */
+    public val clock: Clock
+
+    /**
+     * The machine model of the machine that is running the image.
+     */
+    public val machine: SimMachineModel
+
+    /**
+     * Ask the processor cores to run the specified [slice] and suspend execution until the trigger condition is met as
+     * specified by [triggerMode].
+     *
+     * After the method returns, [Slice.burst] will contain the remaining burst length for each of the cores (which
+     * may be zero). These changes may happen anytime during execution of this method and callers should not rely on
+     * the timing of this change.
+     *
+     * @param slice The representation of work to run on the processors.
+     * @param triggerMode The trigger condition to resume execution.
+     */
+    public suspend fun run(slice: Slice, triggerMode: TriggerMode = TriggerMode.FIRST): Unit =
+        select { onRun(slice, triggerMode).invoke {} }
+
+    /**
+     * Ask the processors cores to run the specified [batch] of work slices and suspend execution until the trigger
+     * condition is met as specified by [triggerMode].
+     *
+     * After the method returns, [Slice.burst] will contain the remaining burst length for each of the cores (which
+     * may be zero). These changes may happen anytime during execution of this method and callers should not rely on
+     * the timing of this change.
+     *
+     * In case slices in the batch do not finish processing before their deadline, [merge] is called to merge these
+     * slices with the next slice to be executed.
+     *
+     * @param batch The batch of work to run on the processors.
+     * @param triggerMode The trigger condition to resume execution.
+     * @param merge The merge function for consecutive slices in case the last slice was not completed within its
+     * deadline.
+     */
+    public suspend fun run(
+        batch: Sequence<Slice>,
+        triggerMode: TriggerMode = TriggerMode.FIRST,
+        merge: (Slice, Slice) -> Slice = { _, r -> r }
+    ): Unit = select { onRun(batch, triggerMode, merge).invoke {} }
+
+    /**
+     * Ask the processor cores to run the specified [slice] and select when the trigger condition is met as specified
+     * by [triggerMode].
+     *
+     * After the method returns, [Slice.burst] will contain the remaining burst length for each of the cores (which
+     * may be zero). These changes may happen anytime during execution of this method and callers should not rely on
+     * the timing of this change.
+     *
+     * @param slice The representation of work to request from the processors.
+     * @param triggerMode The trigger condition to resume execution.
+     */
+    public fun onRun(slice: Slice, triggerMode: TriggerMode = TriggerMode.FIRST): SelectClause0 =
+        onRun(sequenceOf(slice), triggerMode)
+
+    /**
+     * Ask the processors cores to run the specified [batch] of work slices and select when the trigger condition is met
+     * as specified by [triggerMode].
+     *
+     * After the method returns, [Slice.burst] will contain the remaining burst length for each of the cores (which
+     * may be zero). These changes may happen anytime during execution of this method and callers should not rely on
+     * the timing of this change.
+     *
+     * In case slices in the batch do not finish processing before their deadline, [merge] is called to merge these
+     * slices with the next slice to be executed.
+     *
+     * @param batch The batch of work to run on the processors.
+     * @param triggerMode The trigger condition to resume execution during the **last** slice.
+     * @param merge The merge function for consecutive slices in case the last slice was not completed within its
+     * deadline.
+     */
+    public fun onRun(
+        batch: Sequence<Slice>,
+        triggerMode: TriggerMode = TriggerMode.FIRST,
+        merge: (Slice, Slice) -> Slice = { _, r -> r }
+    ): SelectClause0
+
+    /**
+     * A request to the host machine for a slice of CPU time from the processor cores.
+     *
+     * Both [burst] and [limit] must be of the same size and in any other case the method will throw an
+     * [IllegalArgumentException].
+     *
+     *
+     * @param burst The burst time to request from each of the processor cores.
+     * @param limit The maximum usage in terms of MHz that the processing core may use while running the burst.
+     * @param deadline The instant at which this slice needs to be fulfilled.
+     */
+    public class Slice(public val burst: LongArray, public val limit: DoubleArray, public val deadline: Long) {
+        init {
+            require(burst.size == limit.size) { "Incompatible array dimensions" }
+        }
+    }
+
+    /**
+     * The modes for triggering a machine exit from the machine.
+     */
+    public enum class TriggerMode {
+        /**
+         * A machine exit occurs when either the first processor finishes processing a **non-zero** burst or the
+         * deadline is reached.
+         */
+        FIRST,
+
+        /**
+         * A machine exit occurs when either the last processor finishes processing a **non-zero** burst or the deadline
+         * is reached.
+         */
+        LAST,
+
+        /**
+         * A machine exit occurs only when the deadline is reached.
+         */
+        DEADLINE
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimHypervisor.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimHypervisor.kt
new file mode 100644
index 00000000..6087227b
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimHypervisor.kt
@@ -0,0 +1,535 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.intrinsics.startCoroutineCancellable
+import kotlinx.coroutines.selects.SelectClause0
+import kotlinx.coroutines.selects.SelectInstance
+import kotlinx.coroutines.selects.select
+import org.opendc.simulator.compute.interference.PerformanceInterferenceModel
+import org.opendc.simulator.compute.model.ProcessingUnit
+import org.opendc.simulator.compute.workload.SimWorkload
+import java.time.Clock
+import kotlin.math.ceil
+import kotlin.math.max
+import kotlin.math.min
+
+/**
+ * SimHypervisor distributes the computing requirements of multiple [SimWorkload] on a single [SimBareMetalMachine] concurrently.
+ *
+ * @param coroutineScope The [CoroutineScope] to run the simulated workloads in.
+ * @param clock The virtual clock to track the simulation time.
+ */
+@OptIn(ExperimentalCoroutinesApi::class, InternalCoroutinesApi::class)
+public class SimHypervisor(
+    private val coroutineScope: CoroutineScope,
+    private val clock: Clock,
+    private val listener: Listener? = null
+) : SimWorkload {
+    /**
+     * A set for tracking the VM context objects.
+     */
+    private val vms: MutableSet<VmExecutionContext> = mutableSetOf()
+
+    /**
+     * A flag to indicate the driver is stopped.
+     */
+    private var stopped: Boolean = false
+
+    /**
+     * The channel for scheduling new CPU requests.
+     */
+    private val schedulingQueue = Channel<SchedulerCommand>(Channel.UNLIMITED)
+
+    /**
+     * Create a [SimMachine] instance on which users may run a [SimWorkload].
+     *
+     * @param model The machine to create.
+     */
+    public fun createMachine(model: SimMachineModel, performanceInterferenceModel: PerformanceInterferenceModel? = null): SimMachine {
+        val vm = VmSession(model, performanceInterferenceModel)
+        val vmCtx = VmExecutionContext(vm)
+
+        return object : SimMachine {
+            override val model: SimMachineModel
+                get() = vmCtx.machine
+
+            override val usage: StateFlow<Double>
+                get() = vm.usage
+
+            /**
+             * The current active workload.
+             */
+            private var activeWorkload: SimWorkload? = null
+
+            override suspend fun run(workload: SimWorkload) {
+                require(activeWorkload == null) { "Run should not be called concurrently" }
+
+                try {
+                    activeWorkload = workload
+                    workload.run(vmCtx)
+                } finally {
+                    activeWorkload = null
+                }
+            }
+
+            override fun toString(): String = "SimVirtualMachine"
+        }
+    }
+
+    /**
+     * Run the scheduling process of the hypervisor.
+     */
+    override suspend fun run(ctx: SimExecutionContext) {
+        val model = ctx.machine
+        val maxUsage = model.cpus.sumByDouble { it.frequency }
+        val pCPUs = model.cpus.indices.sortedBy { model.cpus[it].frequency }
+
+        val vms = mutableSetOf<VmSession>()
+        val vcpus = mutableListOf<VCpu>()
+
+        val usage = DoubleArray(model.cpus.size)
+        val burst = LongArray(model.cpus.size)
+
+        fun process(command: SchedulerCommand) {
+            when (command) {
+                is SchedulerCommand.Schedule -> {
+                    vms += command.vm
+                    vcpus.addAll(command.vm.vcpus)
+                }
+                is SchedulerCommand.Deschedule -> {
+                    vms -= command.vm
+                    vcpus.removeAll(command.vm.vcpus)
+                }
+                is SchedulerCommand.Interrupt -> {
+                }
+            }
+        }
+
+        fun processRemaining() {
+            var command = schedulingQueue.poll()
+            while (command != null) {
+                process(command)
+                command = schedulingQueue.poll()
+            }
+        }
+
+        while (!stopped) {
+            // Wait for a request to be submitted if we have no work yet.
+            if (vcpus.isEmpty()) {
+                process(schedulingQueue.receive())
+            }
+
+            processRemaining()
+
+            val start = clock.millis()
+
+            var duration: Double = Double.POSITIVE_INFINITY
+            var deadline: Long = Long.MAX_VALUE
+            var availableUsage = maxUsage
+            var totalRequestedUsage = 0.0
+            var totalRequestedBurst = 0L
+
+            // Sort the vCPUs based on their requested usage
+            // Profiling shows that it is faster to sort every slice instead of maintaining some kind of sorted set
+            vcpus.sort()
+
+            // Divide the available host capacity fairly across the vCPUs using max-min fair sharing
+            for ((i, req) in vcpus.withIndex()) {
+                val remaining = vcpus.size - i
+                val availableShare = availableUsage / remaining
+                val grantedUsage = min(req.limit, availableShare)
+
+                // Take into account the minimum deadline of this slice before we possible continue
+                deadline = min(deadline, req.vm.deadline)
+
+                // Ignore empty CPUs
+                if (grantedUsage <= 0 || req.burst <= 0) {
+                    req.allocatedLimit = 0.0
+                    continue
+                }
+
+                totalRequestedUsage += req.limit
+                totalRequestedBurst += req.burst
+
+                req.allocatedLimit = grantedUsage
+                availableUsage -= grantedUsage
+
+                // The duration that we want to run is that of the shortest request from a vCPU
+                duration = min(duration, req.burst / grantedUsage)
+            }
+
+            // XXX We set the minimum duration to 5 minutes here to prevent the rounding issues that are occurring with the FLOPs.
+            duration = 300.0
+
+            val totalAllocatedUsage = maxUsage - availableUsage
+            var totalAllocatedBurst = 0L
+            availableUsage = totalAllocatedUsage
+            val serverLoad = totalAllocatedUsage / maxUsage
+
+            // Divide the requests over the available capacity of the pCPUs fairly
+            for (i in pCPUs) {
+                val maxCpuUsage = model.cpus[i].frequency
+                val fraction = maxCpuUsage / maxUsage
+                val grantedUsage = min(maxCpuUsage, totalAllocatedUsage * fraction)
+                val grantedBurst = ceil(duration * grantedUsage).toLong()
+
+                usage[i] = grantedUsage
+                burst[i] = grantedBurst
+                totalAllocatedBurst += grantedBurst
+                availableUsage -= grantedUsage
+            }
+
+            // We run the total burst on the host processor. Note that this call may be cancelled at any moment in
+            // time, so not all of the burst may be executed.
+            select<Boolean> {
+                schedulingQueue.onReceive { schedulingQueue.offer(it); true }
+                ctx.onRun(SimExecutionContext.Slice(burst, usage, deadline), SimExecutionContext.TriggerMode.DEADLINE)
+                    .invoke { false }
+            }
+
+            val end = clock.millis()
+
+            // No work was performed
+            if ((end - start) <= 0) {
+                continue
+            }
+
+            // The total requested burst that the VMs wanted to run in the time-frame that we ran.
+            val totalRequestedSubBurst =
+                vcpus.map { ceil((duration * 1000) / (it.vm.deadline - start) * it.burst).toLong() }.sum()
+            val totalRemainder = burst.sum()
+            val totalGrantedBurst = totalAllocatedBurst - totalRemainder
+
+            // The burst that was lost due to overcommissioning of CPU resources
+            var totalOvercommissionedBurst = 0L
+            // The burst that was lost due to interference.
+            var totalInterferedBurst = 0L
+
+            val vmIterator = vms.iterator()
+            while (vmIterator.hasNext()) {
+                val vm = vmIterator.next()
+
+                // Apply performance interference model
+                val performanceScore = vm.performanceInterferenceModel?.apply(serverLoad) ?: 1.0
+                var hasFinished = false
+
+                for (vcpu in vm.vcpus) {
+                    // Compute the fraction of compute time allocated to the VM
+                    val fraction = vcpu.allocatedLimit / totalAllocatedUsage
+
+                    // Compute the burst time that the VM was actually granted
+                    val grantedBurst = ceil(totalGrantedBurst * fraction).toLong()
+
+                    // The burst that was actually used by the VM
+                    val usedBurst = ceil(grantedBurst * performanceScore).toLong()
+
+                    totalInterferedBurst += grantedBurst - usedBurst
+
+                    // Compute remaining burst time to be executed for the request
+                    if (vcpu.consume(usedBurst)) {
+                        hasFinished = true
+                    } else if (vm.deadline <= end) {
+                        // Request must have its entire burst consumed or otherwise we have overcommission
+                        // Note that we count the overcommissioned burst if the hypervisor has failed.
+                        totalOvercommissionedBurst += vcpu.burst
+                    }
+                }
+
+                if (hasFinished || vm.deadline <= end) {
+                    // Mark the VM as finished and deschedule the VMs if needed
+                    if (vm.finish()) {
+                        vmIterator.remove()
+                        vcpus.removeAll(vm.vcpus)
+                    }
+                }
+            }
+
+            listener?.onSliceFinish(
+                this,
+                totalRequestedBurst,
+                min(totalRequestedSubBurst, totalGrantedBurst), // We can run more than requested due to timing
+                totalOvercommissionedBurst,
+                totalInterferedBurst, // Might be smaller than zero due to FP rounding errors,
+                min(
+                    totalAllocatedUsage,
+                    totalRequestedUsage
+                ), // The allocated usage might be slightly higher due to FP rounding
+                totalRequestedUsage
+            )
+        }
+    }
+
+    /**
+     * Event listener for hypervisor events.
+     */
+    public interface Listener {
+        /**
+         * This method is invoked when a slice is finished.
+         */
+        public fun onSliceFinish(
+            hypervisor: SimHypervisor,
+            requestedBurst: Long,
+            grantedBurst: Long,
+            overcommissionedBurst: Long,
+            interferedBurst: Long,
+            cpuUsage: Double,
+            cpuDemand: Double
+        )
+    }
+
+    /**
+     * A scheduling command processed by the scheduler.
+     */
+    private sealed class SchedulerCommand {
+        /**
+         * Schedule the specified VM on the hypervisor.
+         */
+        data class Schedule(val vm: VmSession) : SchedulerCommand()
+
+        /**
+         * De-schedule the specified VM on the hypervisor.
+         */
+        data class Deschedule(val vm: VmSession) : SchedulerCommand()
+
+        /**
+         * Interrupt the scheduler.
+         */
+        object Interrupt : SchedulerCommand()
+    }
+
+    /**
+     * A virtual machine running on the hypervisor.
+     *
+     * @param ctx The execution context the vCPU runs in.
+     * @param triggerMode The mode when to trigger the VM exit.
+     * @param merge The function to merge consecutive slices on spillover.
+     * @param select The function to select on finish.
+     */
+    @OptIn(InternalCoroutinesApi::class)
+    private data class VmSession(
+        val model: SimMachineModel,
+        val performanceInterferenceModel: PerformanceInterferenceModel? = null,
+        var triggerMode: SimExecutionContext.TriggerMode = SimExecutionContext.TriggerMode.FIRST,
+        var merge: (SimExecutionContext.Slice, SimExecutionContext.Slice) -> SimExecutionContext.Slice = { _, r -> r },
+        var select: () -> Unit = {}
+    ) {
+        /**
+         * The vCPUs of this virtual machine.
+         */
+        val vcpus: List<VCpu>
+
+        /**
+         * The slices that the VM wants to run.
+         */
+        var queue: Iterator<SimExecutionContext.Slice> = emptyList<SimExecutionContext.Slice>().iterator()
+
+        /**
+         * The current active slice.
+         */
+        var activeSlice: SimExecutionContext.Slice? = null
+
+        /**
+         * The current deadline of the VM.
+         */
+        val deadline: Long
+            get() = activeSlice?.deadline ?: Long.MAX_VALUE
+
+        /**
+         * A flag to indicate that the VM is idle.
+         */
+        val isIdle: Boolean
+            get() = activeSlice == null
+
+        /**
+         * The usage of the virtual machine.
+         */
+        val usage: MutableStateFlow<Double> = MutableStateFlow(0.0)
+
+        init {
+            vcpus = model.cpus.mapIndexed { i, model -> VCpu(this, model, i) }
+        }
+
+        /**
+         * Schedule the given slices on this vCPU, replacing the existing slices.
+         */
+        fun schedule(slices: Sequence<SimExecutionContext.Slice>) {
+            queue = slices.iterator()
+
+            if (queue.hasNext()) {
+                activeSlice = queue.next()
+                refresh()
+            }
+        }
+
+        /**
+         * Cancel the existing workload on the VM.
+         */
+        fun cancel() {
+            queue = emptyList<SimExecutionContext.Slice>().iterator()
+            activeSlice = null
+            refresh()
+        }
+
+        /**
+         * Finish the current slice of the VM.
+         *
+         * @return `true` if the vCPUs may be descheduled, `false` otherwise.
+         */
+        fun finish(): Boolean {
+            val activeSlice = activeSlice ?: return true
+
+            return if (queue.hasNext()) {
+                val needsMerge = activeSlice.burst.any { it > 0 }
+                val candidateSlice = queue.next()
+                val slice = if (needsMerge) merge(activeSlice, candidateSlice) else candidateSlice
+
+                this.activeSlice = slice
+
+                // Update the vCPU cache
+                refresh()
+
+                false
+            } else {
+                this.activeSlice = null
+                select()
+                true
+            }
+        }
+
+        /**
+         * Refresh the vCPU cache.
+         */
+        fun refresh() {
+            vcpus.forEach { it.refresh() }
+            usage.value = vcpus.sumByDouble { it.burst / it.limit } / vcpus.size
+        }
+    }
+
+    /**
+     * A virtual CPU that can be scheduled on a physical CPU.
+     *
+     * @param vm The VM of which this vCPU is part.
+     * @param model The model of CPU that this vCPU models.
+     * @param id The id of the vCPU with respect to the VM.
+     */
+    private data class VCpu(
+        val vm: VmSession,
+        val model: ProcessingUnit,
+        val id: Int
+    ) : Comparable<VCpu> {
+        /**
+         * The current limit on the vCPU.
+         */
+        var limit: Double = 0.0
+
+        /**
+         * The limit allocated by the hypervisor.
+         */
+        var allocatedLimit: Double = 0.0
+
+        /**
+         * The current burst running on the vCPU.
+         */
+        var burst: Long = 0L
+
+        /**
+         * Consume the specified burst on this vCPU.
+         */
+        fun consume(burst: Long): Boolean {
+            this.burst = max(0, this.burst - burst)
+
+            // Flush the result to the slice if it exists
+            vm.activeSlice?.burst?.takeIf { id < it.size }?.set(id, this.burst)
+
+            return allocatedLimit > 0.0 && this.burst == 0L
+        }
+
+        /**
+         * Refresh the information of this vCPU based on the current slice.
+         */
+        fun refresh() {
+            limit = vm.activeSlice?.limit?.takeIf { id < it.size }?.get(id) ?: 0.0
+            burst = vm.activeSlice?.burst?.takeIf { id < it.size }?.get(id) ?: 0
+        }
+
+        /**
+         * Compare to another vCPU based on the current load of the vCPU.
+         */
+        override fun compareTo(other: VCpu): Int {
+            return limit.compareTo(other.limit)
+        }
+
+        /**
+         * Create a string representation of the vCPU.
+         */
+        override fun toString(): String =
+            "vCPU(id=$id,burst=$burst,limit=$limit,allocatedLimit=$allocatedLimit)"
+    }
+
+    /**
+     * The execution context in which a VM runs.
+     *
+     */
+    private inner class VmExecutionContext(val session: VmSession) :
+        SimExecutionContext, DisposableHandle {
+        override val machine: SimMachineModel
+            get() = session.model
+
+        override val clock: Clock
+            get() = this@SimHypervisor.clock
+
+        @OptIn(InternalCoroutinesApi::class)
+        override fun onRun(
+            batch: Sequence<SimExecutionContext.Slice>,
+            triggerMode: SimExecutionContext.TriggerMode,
+            merge: (SimExecutionContext.Slice, SimExecutionContext.Slice) -> SimExecutionContext.Slice
+        ): SelectClause0 = object : SelectClause0 {
+            @InternalCoroutinesApi
+            override fun <R> registerSelectClause0(select: SelectInstance<R>, block: suspend () -> R) {
+                session.triggerMode = triggerMode
+                session.merge = merge
+                session.select = {
+                    if (select.trySelect()) {
+                        block.startCoroutineCancellable(select.completion)
+                    }
+                }
+                session.schedule(batch)
+                // Indicate to the hypervisor that the VM should be re-scheduled
+                schedulingQueue.offer(SchedulerCommand.Schedule(session))
+                select.disposeOnSelect(this@VmExecutionContext)
+            }
+        }
+
+        override fun dispose() {
+            if (!session.isIdle) {
+                session.cancel()
+                schedulingQueue.offer(SchedulerCommand.Deschedule(session))
+            }
+        }
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt
new file mode 100644
index 00000000..f66085af
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.StateFlow
+import org.opendc.simulator.compute.workload.SimWorkload
+
+/**
+ * A generic machine that is able to run a [SimWorkload].
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+public interface SimMachine {
+    /**
+     * The model of the machine containing its specifications.
+     */
+    public val model: SimMachineModel
+
+    /**
+     * A [StateFlow] representing the CPU usage of the simulated machine.
+     */
+    public val usage: StateFlow<Double>
+
+    /**
+     * Run the specified [SimWorkload] on this machine and suspend execution util the workload has finished.
+     */
+    public suspend fun run(workload: SimWorkload)
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachineModel.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachineModel.kt
new file mode 100644
index 00000000..c2988b11
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachineModel.kt
@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import org.opendc.simulator.compute.model.MemoryUnit
+import org.opendc.simulator.compute.model.ProcessingUnit
+
+/**
+ * A description of the physical or virtual machine on which a bootable image runs.
+ *
+ * @property cpus The list of processing units available to the image.
+ * @property memory The list of memory units available to the image.
+ */
+public data class SimMachineModel(public val cpus: List<ProcessingUnit>, public val memory: List<MemoryUnit>)
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/interference/PerformanceInterferenceModel.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/interference/PerformanceInterferenceModel.kt
new file mode 100644
index 00000000..4c409887
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/interference/PerformanceInterferenceModel.kt
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.interference
+
+import java.util.*
+import kotlin.random.Random
+
+/**
+ * Meta-data key for the [PerformanceInterferenceModel] of an image.
+ */
+public const val IMAGE_PERF_INTERFERENCE_MODEL: String = "image:performance-interference"
+
+/**
+ * Performance Interference Model describing the variability incurred by different sets of workloads if colocated.
+ *
+ * @param items The [PerformanceInterferenceModel.Item]s that make up this model.
+ */
+public class PerformanceInterferenceModel(
+    public val items: SortedSet<Item>,
+    private val random: Random = Random(0)
+) {
+    private var intersectingItems: List<Item> = emptyList()
+    private val colocatedWorkloads = TreeMap<String, Int>()
+
+    /**
+     * Indicate that a VM has started.
+     */
+    public fun onStart(name: String) {
+        colocatedWorkloads.merge(name, 1, Int::plus)
+        intersectingItems = items.filter { item -> doesMatch(item) }
+    }
+
+    /**
+     * Indicate that a VM has stopped.
+     */
+    public fun onStop(name: String) {
+        colocatedWorkloads.computeIfPresent(name) { _, v -> (v - 1).takeUnless { it == 0 } }
+        intersectingItems = items.filter { item -> doesMatch(item) }
+    }
+
+    /**
+     * Compute the performance interference based on the current server load.
+     */
+    public fun apply(currentServerLoad: Double): Double {
+        if (intersectingItems.isEmpty()) {
+            return 1.0
+        }
+        val score = intersectingItems
+            .firstOrNull { it.minServerLoad <= currentServerLoad }
+
+        // Apply performance penalty to (on average) only one of the VMs
+        return if (score != null && random.nextInt(score.workloadNames.size) == 0) {
+            score.performanceScore
+        } else {
+            1.0
+        }
+    }
+
+    private fun doesMatch(item: Item): Boolean {
+        var count = 0
+        for (
+            name in item.workloadNames.subSet(
+                colocatedWorkloads.firstKey(),
+                colocatedWorkloads.lastKey() + "\u0000"
+            )
+        ) {
+            count += colocatedWorkloads.getOrDefault(name, 0)
+            if (count > 1)
+                return true
+        }
+        return false
+    }
+
+    /**
+     * Model describing how a specific set of workloads causes performance variability for each workload.
+     *
+     * @param workloadNames The names of the workloads that together cause performance variability for each workload in the set.
+     * @param minServerLoad The minimum total server load at which this interference is activated and noticeable.
+     * @param performanceScore The performance score that should be applied to each workload's performance. 1 means no
+     * influence, <1 means that performance degrades, and >1 means that performance improves.
+     */
+    public data class Item(
+        public val workloadNames: SortedSet<String>,
+        public val minServerLoad: Double,
+        public val performanceScore: Double
+    ) : Comparable<Item> {
+        override fun equals(other: Any?): Boolean {
+            if (this === other) return true
+            if (javaClass != other?.javaClass) return false
+
+            other as Item
+
+            if (workloadNames != other.workloadNames) return false
+
+            return true
+        }
+
+        override fun hashCode(): Int = workloadNames.hashCode()
+
+        override fun compareTo(other: Item): Int {
+            var cmp = performanceScore.compareTo(other.performanceScore)
+            if (cmp != 0) {
+                return cmp
+            }
+
+            cmp = minServerLoad.compareTo(other.minServerLoad)
+            if (cmp != 0) {
+                return cmp
+            }
+
+            return hashCode().compareTo(other.hashCode())
+        }
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/MemoryUnit.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/MemoryUnit.kt
new file mode 100644
index 00000000..bcbde5b1
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/MemoryUnit.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.model
+
+/**
+ * A memory unit of a compute resource, either virtual or physical.
+ *
+ * @property vendor The vendor string of the memory.
+ * @property modelName The name of the memory model.
+ * @property speed The access speed of the memory in MHz.
+ * @property size The size of the memory unit in MBs.
+ */
+public data class MemoryUnit(
+    public val vendor: String,
+    public val modelName: String,
+    public val speed: Double,
+    public val size: Long
+)
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingNode.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingNode.kt
new file mode 100644
index 00000000..58ed816c
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingNode.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.model
+
+/**
+ * A processing node/package/socket containing possibly several CPU cores.
+ *
+ * @property vendor The vendor string of the processor node.
+ * @property modelName The name of the processor node.
+ * @property arch The micro-architecture of the processor node.
+ * @property coreCount The number of logical CPUs in the processor node.
+ */
+public data class ProcessingNode(
+    public val vendor: String,
+    public val arch: String,
+    public val modelName: String,
+    public val coreCount: Int
+)
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingUnit.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingUnit.kt
new file mode 100644
index 00000000..415e95e6
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/model/ProcessingUnit.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.model
+
+/**
+ * A single logical compute unit of processor node, either virtual or physical.
+ *
+ * @property node The processing node containing the CPU core.
+ * @property id The identifier of the CPU core within the processing node.
+ * @property frequency The clock rate of the CPU in MHz.
+ */
+public data class ProcessingUnit(
+    public val node: ProcessingNode,
+    public val id: Int,
+    public val frequency: Double
+)
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkload.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkload.kt
new file mode 100644
index 00000000..918a78bd
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkload.kt
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.workload
+
+import org.opendc.simulator.compute.SimExecutionContext
+import kotlin.math.min
+
+/**
+ * A [SimWorkload] that models applications performing a static number of floating point operations ([flops]) on
+ * a compute resource.
+ *
+ * @property flops The number of floating point operations to perform for this task in MFLOPs.
+ * @property cores The number of cores that the image is able to utilize.
+ * @property utilization A model of the CPU utilization of the application.
+ */
+public class SimFlopsWorkload(
+    public val flops: Long,
+    public val cores: Int,
+    public val utilization: Double = 0.8
+) : SimWorkload {
+    init {
+        require(flops >= 0) { "Negative number of flops" }
+        require(cores > 0) { "Negative number of cores or no cores" }
+        require(utilization > 0.0 && utilization <= 1.0) { "Utilization must be in (0, 1]" }
+    }
+
+    /**
+     * Execute the runtime behavior based on a number of floating point operations to execute.
+     */
+    override suspend fun run(ctx: SimExecutionContext) {
+        val cores = min(this.cores, ctx.machine.cpus.size)
+        val burst = LongArray(cores) { flops / cores }
+        val maxUsage = DoubleArray(cores) { i -> ctx.machine.cpus[i].frequency * utilization }
+
+        ctx.run(SimExecutionContext.Slice(burst, maxUsage, Long.MAX_VALUE), triggerMode = SimExecutionContext.TriggerMode.LAST)
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
new file mode 100644
index 00000000..7b1ddf32
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimTraceWorkload.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.workload
+
+import org.opendc.simulator.compute.SimExecutionContext
+import kotlin.math.min
+
+/**
+ * A [SimWorkload] that replays a workload trace consisting of multiple fragments, each indicating the resource
+ * consumption for some period of time.
+ */
+public class SimTraceWorkload(public val trace: Sequence<Fragment>) : SimWorkload {
+    override suspend fun run(ctx: SimExecutionContext) {
+        var offset = ctx.clock.millis()
+
+        val batch = trace.map { fragment ->
+            val cores = min(fragment.cores, ctx.machine.cpus.size)
+            val burst = LongArray(cores) { fragment.flops / cores }
+            val usage = DoubleArray(cores) { fragment.usage / cores }
+            offset += fragment.duration
+            SimExecutionContext.Slice(burst, usage, offset)
+        }
+
+        ctx.run(batch)
+    }
+
+    override fun toString(): String = "SimTraceWorkload"
+
+    /**
+     * A fragment of the workload.
+     */
+    public data class Fragment(val time: Long, val flops: Long, val duration: Long, val usage: Double, val cores: Int)
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimWorkload.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimWorkload.kt
new file mode 100644
index 00000000..2add8cce
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/workload/SimWorkload.kt
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.workload
+
+import org.opendc.simulator.compute.SimExecutionContext
+
+/**
+ * A model that characterizes the runtime behavior of some particular workload.
+ *
+ * Workloads are stateful objects that may be paused and resumed at a later moment. As such, be careful when using the
+ * same [SimWorkload] from multiple contexts as only a single concurrent [run] call is expected.
+ */
+public interface SimWorkload {
+    /**
+     * Launch the workload in the specified [SimExecutionContext].
+     *
+     * This method should encapsulate and characterize the runtime behavior of the instance resulting from launching
+     * the workload on some machine, in terms of the resource consumption on the machine.
+     */
+    public suspend fun run(ctx: SimExecutionContext)
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimHypervisorTest.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimHypervisorTest.kt
new file mode 100644
index 00000000..78bd2940
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimHypervisorTest.kt
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.TestCoroutineScope
+import kotlinx.coroutines.yield
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertAll
+import org.opendc.simulator.compute.model.MemoryUnit
+import org.opendc.simulator.compute.model.ProcessingNode
+import org.opendc.simulator.compute.model.ProcessingUnit
+import org.opendc.simulator.compute.workload.SimTraceWorkload
+import org.opendc.simulator.utils.DelayControllerClockAdapter
+import java.time.Clock
+
+/**
+ * Test suite for the [SimHypervisor] class.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+internal class SimHypervisorTest {
+    private lateinit var scope: TestCoroutineScope
+    private lateinit var clock: Clock
+    private lateinit var machineModel: SimMachineModel
+
+    @BeforeEach
+    fun setUp() {
+        scope = TestCoroutineScope()
+        clock = DelayControllerClockAdapter(scope)
+
+        val cpuNode = ProcessingNode("Intel", "Xeon", "amd64", 2)
+        machineModel = SimMachineModel(
+            cpus = List(cpuNode.coreCount) { ProcessingUnit(cpuNode, it, 3200.0) },
+            memory = List(4) { MemoryUnit("Crucial", "MTA18ASF4G72AZ-3G2B1", 3200.0, 32_000) }
+        )
+    }
+
+    /**
+     * Test overcommissioning of a hypervisor.
+     */
+    @Test
+    fun overcommission() {
+        val listener = object : SimHypervisor.Listener {
+            var totalRequestedBurst = 0L
+            var totalGrantedBurst = 0L
+            var totalOvercommissionedBurst = 0L
+
+            override fun onSliceFinish(
+                hypervisor: SimHypervisor,
+                requestedBurst: Long,
+                grantedBurst: Long,
+                overcommissionedBurst: Long,
+                interferedBurst: Long,
+                cpuUsage: Double,
+                cpuDemand: Double
+            ) {
+                totalRequestedBurst += requestedBurst
+                totalGrantedBurst += grantedBurst
+                totalOvercommissionedBurst += overcommissionedBurst
+            }
+        }
+
+        scope.launch {
+            val duration = 5 * 60L
+            val workloadA =
+                SimTraceWorkload(
+                    sequenceOf(
+                        SimTraceWorkload.Fragment(0, 28L * duration, duration * 1000, 28.0, 2),
+                        SimTraceWorkload.Fragment(0, 3500L * duration, duration * 1000, 3500.0, 2),
+                        SimTraceWorkload.Fragment(0, 0, duration * 1000, 0.0, 2),
+                        SimTraceWorkload.Fragment(0, 183L * duration, duration * 1000, 183.0, 2)
+                    ),
+                )
+            val workloadB =
+                SimTraceWorkload(
+                    sequenceOf(
+                        SimTraceWorkload.Fragment(0, 28L * duration, duration * 1000, 28.0, 2),
+                        SimTraceWorkload.Fragment(0, 3100L * duration, duration * 1000, 3100.0, 2),
+                        SimTraceWorkload.Fragment(0, 0, duration * 1000, 0.0, 2),
+                        SimTraceWorkload.Fragment(0, 73L * duration, duration * 1000, 73.0, 2)
+                    )
+                )
+
+            val machine = SimBareMetalMachine(scope, clock, machineModel)
+            val hypervisor = SimHypervisor(scope, clock, listener)
+
+            launch {
+                machine.run(hypervisor)
+            }
+
+            yield()
+            launch { hypervisor.createMachine(machineModel).run(workloadA) }
+            launch { hypervisor.createMachine(machineModel).run(workloadB) }
+        }
+
+        scope.advanceUntilIdle()
+
+        assertAll(
+            { Assertions.assertEquals(emptyList<Throwable>(), scope.uncaughtExceptions, "No errors") },
+            { Assertions.assertEquals(2073600, listener.totalRequestedBurst, "Requested Burst does not match") },
+            { Assertions.assertEquals(2013600, listener.totalGrantedBurst, "Granted Burst does not match") },
+            { Assertions.assertEquals(60000, listener.totalOvercommissionedBurst, "Overcommissioned Burst does not match") },
+            { Assertions.assertEquals(1200001, scope.currentTime) }
+        )
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
new file mode 100644
index 00000000..332ca8e9
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.test.TestCoroutineScope
+import kotlinx.coroutines.test.runBlockingTest
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.opendc.simulator.compute.model.MemoryUnit
+import org.opendc.simulator.compute.model.ProcessingNode
+import org.opendc.simulator.compute.model.ProcessingUnit
+import org.opendc.simulator.compute.workload.SimFlopsWorkload
+import org.opendc.simulator.utils.DelayControllerClockAdapter
+
+/**
+ * Test suite for the [SimBareMetalMachine] class.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class SimMachineTest {
+    private lateinit var machineModel: SimMachineModel
+
+    @BeforeEach
+    fun setUp() {
+        val cpuNode = ProcessingNode("Intel", "Xeon", "amd64", 2)
+
+        machineModel = SimMachineModel(
+            cpus = List(cpuNode.coreCount) { ProcessingUnit(cpuNode, it, 1000.0) },
+            memory = List(4) { MemoryUnit("Crucial", "MTA18ASF4G72AZ-3G2B1", 3200.0, 32_000) }
+        )
+    }
+
+    @Test
+    fun testFlopsWorkload() {
+        val testScope = TestCoroutineScope()
+        val clock = DelayControllerClockAdapter(testScope)
+        val machine = SimBareMetalMachine(testScope, clock, machineModel)
+
+        testScope.runBlockingTest {
+            machine.run(SimFlopsWorkload(2_000, 2, utilization = 1.0))
+
+            // Two cores execute 1000 MFlOps per second (1000 ms)
+            assertEquals(1000, testScope.currentTime)
+        }
+    }
+
+    @Test
+    fun testUsage() {
+        val testScope = TestCoroutineScope()
+        val clock = DelayControllerClockAdapter(testScope)
+        val machine = SimBareMetalMachine(testScope, clock, machineModel)
+
+        testScope.runBlockingTest {
+            machine.run(SimFlopsWorkload(2_000, 2, utilization = 1.0))
+            assertEquals(1.0, machine.usage.value)
+
+            // Wait for the usage to reset
+            delay(1)
+            assertEquals(0.0, machine.usage.value)
+        }
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkloadTest.kt b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkloadTest.kt
new file mode 100644
index 00000000..51bed76c
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/workload/SimFlopsWorkloadTest.kt
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.compute.workload
+
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+
+/**
+ * Test suite for [SimFlopsWorkload] class.
+ */
+class SimFlopsWorkloadTest {
+    @Test
+    fun testFlopsNonNegative() {
+        assertThrows<IllegalArgumentException>("FLOPs must be non-negative") {
+            SimFlopsWorkload(-1, 1)
+        }
+    }
+
+    @Test
+    fun testCoresNonZero() {
+        assertThrows<IllegalArgumentException>("Cores cannot be zero") {
+            SimFlopsWorkload(1, 0)
+        }
+    }
+
+    @Test
+    fun testCoresPositive() {
+        assertThrows<IllegalArgumentException>("Cores cannot be negative") {
+            SimFlopsWorkload(1, -1)
+        }
+    }
+
+    @Test
+    fun testUtilizationNonZero() {
+        assertThrows<IllegalArgumentException>("Utilization cannot be zero") {
+            SimFlopsWorkload(1, 1, 0.0)
+        }
+    }
+
+    @Test
+    fun testUtilizationPositive() {
+        assertThrows<IllegalArgumentException>("Utilization cannot be negative") {
+            SimFlopsWorkload(1, 1, -1.0)
+        }
+    }
+
+    @Test
+    fun testUtilizationNotLargerThanOne() {
+        assertThrows<IllegalArgumentException>("Utilization cannot be larger than one") {
+            SimFlopsWorkload(1, 1, 2.0)
+        }
+    }
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-core/build.gradle.kts b/simulator/opendc-simulator/opendc-simulator-core/build.gradle.kts
new file mode 100644
index 00000000..a740dcf3
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-core/build.gradle.kts
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+description = "Simulation-specific code for use in OpenDC"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-convention`
+}
+
+dependencies {
+    api("org.jetbrains.kotlinx:kotlinx-coroutines-test:${Library.KOTLINX_COROUTINES}")
+}
diff --git a/simulator/opendc-simulator/src/main/kotlin/org/opendc/simulator/utils/DelayControllerClockAdapter.kt b/simulator/opendc-simulator/opendc-simulator-core/src/main/kotlin/org/opendc/simulator/utils/DelayControllerClockAdapter.kt
index 84c18e87..84c18e87 100644
--- a/simulator/opendc-simulator/src/main/kotlin/org/opendc/simulator/utils/DelayControllerClockAdapter.kt
+++ b/simulator/opendc-simulator/opendc-simulator-core/src/main/kotlin/org/opendc/simulator/utils/DelayControllerClockAdapter.kt
diff --git a/simulator/opendc-simulator/opendc-simulator-failures/build.gradle.kts b/simulator/opendc-simulator/opendc-simulator-failures/build.gradle.kts
new file mode 100644
index 00000000..1c30506f
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-failures/build.gradle.kts
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+description = "Failure models for OpenDC"
+
+plugins {
+    `kotlin-library-convention`
+}
+
+dependencies {
+    api("org.jetbrains.kotlinx:kotlinx-coroutines-core:${Library.KOTLINX_COROUTINES}")
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/CorrelatedFaultInjector.kt b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/CorrelatedFaultInjector.kt
new file mode 100644
index 00000000..0e15f338
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/CorrelatedFaultInjector.kt
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.failures
+
+import kotlinx.coroutines.*
+import java.time.Clock
+import kotlin.math.exp
+import kotlin.math.max
+import kotlin.random.Random
+import kotlin.random.asJavaRandom
+
+/**
+ * A [FaultInjector] that injects fault in the system which are correlated to each other. Failures do not occur in
+ * isolation, but will trigger other faults.
+ */
+public class CorrelatedFaultInjector(
+    private val coroutineScope: CoroutineScope,
+    private val clock: Clock,
+    private val iatScale: Double,
+    private val iatShape: Double,
+    private val sizeScale: Double,
+    private val sizeShape: Double,
+    private val dScale: Double,
+    private val dShape: Double,
+    random: Random = Random(0)
+) : FaultInjector {
+    /**
+     * The active failure domains that have been registered.
+     */
+    private val active = mutableSetOf<FailureDomain>()
+
+    /**
+     * The [Job] that awaits the nearest fault in the system.
+     */
+    private var job: Job? = null
+
+    /**
+     * The [Random] instance to use.
+     */
+    private val random: java.util.Random = random.asJavaRandom()
+
+    /**
+     * Enqueue the specified [FailureDomain] to fail some time in the future.
+     */
+    override fun enqueue(domain: FailureDomain) {
+        active += domain
+
+        // Clean up the domain if it finishes
+        domain.scope.coroutineContext[Job]!!.invokeOnCompletion {
+            this@CorrelatedFaultInjector.coroutineScope.launch {
+                active -= domain
+
+                if (active.isEmpty()) {
+                    job?.cancel()
+                    job = null
+                }
+            }
+        }
+
+        if (job != null) {
+            return
+        }
+
+        job = this.coroutineScope.launch {
+            while (active.isNotEmpty()) {
+                ensureActive()
+
+                // Make sure to convert delay from hours to milliseconds
+                val d = lognvariate(iatScale, iatShape) * 3.6e6
+
+                // Handle long overflow
+                if (clock.millis() + d <= 0) {
+                    return@launch
+                }
+
+                delay(d.toLong())
+
+                val n = lognvariate(sizeScale, sizeShape).toInt()
+                val targets = active.shuffled(random).take(n)
+
+                for (failureDomain in targets) {
+                    active -= failureDomain
+                    failureDomain.fail()
+                }
+
+                val df = max(lognvariate(dScale, dShape) * 6e4, 15 * 6e4)
+
+                // Handle long overflow
+                if (clock.millis() + df <= 0) {
+                    return@launch
+                }
+
+                delay(df.toLong())
+
+                for (failureDomain in targets) {
+                    failureDomain.recover()
+
+                    // Re-enqueue machine to be failed
+                    enqueue(failureDomain)
+                }
+            }
+
+            job = null
+        }
+    }
+
+    // XXX We should extract this in some common package later on.
+    private fun lognvariate(scale: Double, shape: Double) = exp(scale + shape * random.nextGaussian())
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FailureDomain.kt b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FailureDomain.kt
new file mode 100644
index 00000000..dc3006e8
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FailureDomain.kt
@@ -0,0 +1,47 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 atlarge-research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.failures
+
+import kotlinx.coroutines.CoroutineScope
+
+/**
+ * A logical or physical component in a computing environment which may fail.
+ */
+public interface FailureDomain {
+    /**
+     * The lifecycle of the failure domain to which a [FaultInjector] will attach.
+     */
+    public val scope: CoroutineScope
+
+    /**
+     * Fail the domain externally.
+     */
+    public suspend fun fail()
+
+    /**
+     * Resume the failure domain.
+     */
+    public suspend fun recover()
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FaultInjector.kt b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FaultInjector.kt
new file mode 100644
index 00000000..a866260c
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/FaultInjector.kt
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.failures
+
+/**
+ * An interface for stochastically injecting faults into a running system.
+ */
+public interface FaultInjector {
+    /**
+     * Enqueue the specified [FailureDomain] into the queue as candidate for failure injection in the future.
+     */
+    public fun enqueue(domain: FailureDomain)
+}
diff --git a/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/UncorrelatedFaultInjector.kt b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/UncorrelatedFaultInjector.kt
new file mode 100644
index 00000000..b3bd737e
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-failures/src/main/kotlin/org/opendc/simulator/failures/UncorrelatedFaultInjector.kt
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2020 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.failures
+
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import java.time.Clock
+import kotlin.math.ln1p
+import kotlin.math.pow
+import kotlin.random.Random
+
+/**
+ * A [FaultInjector] that injects uncorrelated faults into the system, meaning that failures of the subsystems are
+ * independent.
+ */
+public class UncorrelatedFaultInjector(
+    private val clock: Clock,
+    private val alpha: Double,
+    private val beta: Double,
+    private val random: Random = Random(0)
+) : FaultInjector {
+    /**
+     * Enqueue the specified [FailureDomain] to fail some time in the future.
+     */
+    override fun enqueue(domain: FailureDomain) {
+        domain.scope.launch {
+            val d = random.weibull(alpha, beta) * 1e3 // Make sure to convert delay to milliseconds
+
+            // Handle long overflow
+            if (clock.millis() + d <= 0) {
+                return@launch
+            }
+
+            delay(d.toLong())
+            domain.fail()
+        }
+    }
+
+    // XXX We should extract this in some common package later on.
+    private fun Random.weibull(alpha: Double, beta: Double) = (beta * (-ln1p(-nextDouble())).pow(1.0 / alpha))
+}