refactor(simulator): Remove usage and speed fields from SimMachine

This change removes the usage and speed fields from SimMachine. We
currently use other ways to capture the usage and speed and these fields
cause an additional maintenance burden and performance impact. Hence the
removal of these fields.

8 files changed, 22 insertions, 119 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractMachine.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractMachine.kt
index f416643e..266db0dd 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractMachine.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractMachine.kt
@@ -23,8 +23,6 @@
 package org.opendc.simulator.compute
 
 import kotlinx.coroutines.*
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
 import org.opendc.simulator.compute.device.SimNetworkAdapter
 import org.opendc.simulator.compute.device.SimPeripheral
 import org.opendc.simulator.compute.model.MachineModel
@@ -49,20 +47,6 @@ public abstract class SimAbstractMachine(
     final override val model: MachineModel
 ) : SimMachine, SimResourceSystem {
     /**
-     * A [StateFlow] representing the CPU usage of the simulated machine.
-     */
-    private val _usage = MutableStateFlow(0.0)
-    public final override val usage: StateFlow<Double>
-        get() = _usage
-
-    /**
-     * The speed of the CPU cores.
-     */
-    public val speed: DoubleArray
-        get() = _speed
-    private var _speed = doubleArrayOf()
-
-    /**
      * The resources allocated for this machine.
      */
     protected abstract val cpus: List<SimProcessingUnit>
@@ -106,10 +90,6 @@ public abstract class SimAbstractMachine(
 
         val ctx = Context(meta)
 
-        // Before the workload starts, initialize the initial power draw
-        _speed = DoubleArray(model.cpus.size) { 0.0 }
-        updateUsage(0.0)
-
         return suspendCancellableCoroutine { cont ->
             this.cont = cont
 
@@ -136,26 +116,6 @@ public abstract class SimAbstractMachine(
         cancel()
     }
 
-    /* SimResourceSystem */
-    override fun onConverge(timestamp: Long) {
-        val totalCapacity = model.cpus.sumOf { it.frequency }
-        val cpus = cpus
-        var totalSpeed = 0.0
-        for (cpu in cpus) {
-            _speed[cpu.model.id] = cpu.speed
-            totalSpeed += cpu.speed
-        }
-
-        updateUsage(totalSpeed / totalCapacity)
-    }
-
-    /**
-     * This method is invoked when the usage of the machine is updated.
-     */
-    protected open fun updateUsage(usage: Double) {
-        _usage.value = usage
-    }
-
     /**
      * Cancel the workload that is currently running on the machine.
      */
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt
index 887f0885..2c711945 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimBareMetalMachine.kt
@@ -32,7 +32,7 @@ import org.opendc.simulator.resources.SimResourceInterpreter
 /**
  * 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
+ * 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 interpreter The [SimResourceInterpreter] to drive the simulation.
@@ -55,13 +55,17 @@ public class SimBareMetalMachine(
         Cpu(SimResourceSource(cpu.frequency, interpreter, this@SimBareMetalMachine), cpu)
     }
 
-    override fun updateUsage(usage: Double) {
-        super.updateUsage(usage)
+    /**
+     * The logic of the power driver.
+     */
+    private val powerDriverLogic = powerDriver.createLogic(this, cpus)
+
+    override fun onConverge(timestamp: Long) {
         psu.update()
     }
 
     init {
-        psu.connect(powerDriver.createLogic(this, cpus))
+        psu.connect(powerDriverLogic)
     }
 
     /**
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt
index 0f4674d5..d8dd8205 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimMachine.kt
@@ -22,7 +22,6 @@
 
 package org.opendc.simulator.compute
 
-import kotlinx.coroutines.flow.StateFlow
 import org.opendc.simulator.compute.device.SimPeripheral
 import org.opendc.simulator.compute.model.MachineModel
 import org.opendc.simulator.compute.workload.SimWorkload
@@ -42,11 +41,6 @@ public interface SimMachine : AutoCloseable {
     public val peripherals: List<SimPeripheral>
 
     /**
-     * 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, meta: Map<String, Any> = emptyMap())
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
index 6002270a..98271fb0 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/kernel/SimAbstractHypervisor.kt
@@ -145,6 +145,8 @@ public abstract class SimAbstractHypervisor(
                 interferenceDomain?.leave(interferenceKey)
             }
         }
+
+        override fun onConverge(timestamp: Long) {}
     }
 
     /**
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
index e43c89ac..bf7aeff1 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
@@ -30,8 +30,17 @@ import org.opendc.simulator.compute.SimProcessingUnit
  */
 public class SimplePowerDriver(private val model: PowerModel) : PowerDriver {
     override fun createLogic(machine: SimMachine, cpus: List<SimProcessingUnit>): PowerDriver.Logic = object : PowerDriver.Logic {
+
         override fun computePower(): Double {
-            return model.computePower(machine.usage.value)
+            var targetFreq = 0.0
+            var totalSpeed = 0.0
+
+            for (cpu in cpus) {
+                targetFreq += cpu.capacity
+                totalSpeed += cpu.speed
+            }
+
+            return model.computePower(totalSpeed / targetFreq)
         }
     }
 
diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
index 19808a77..81268879 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/SimMachineTest.kt
@@ -23,9 +23,7 @@
 package org.opendc.simulator.compute
 
 import kotlinx.coroutines.*
-import kotlinx.coroutines.flow.toList
 import org.junit.jupiter.api.*
-import org.junit.jupiter.api.Assertions.assertArrayEquals
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.opendc.simulator.compute.device.SimNetworkAdapter
 import org.opendc.simulator.compute.model.*
@@ -101,45 +99,6 @@ class SimMachineTest {
     }
 
     @Test
-    fun testUsage() = runBlockingSimulation {
-        val machine = SimBareMetalMachine(
-            SimResourceInterpreter(coroutineContext, clock),
-            machineModel,
-            SimplePowerDriver(ConstantPowerModel(0.0))
-        )
-
-        val res = mutableListOf<Double>()
-        val job = launch { machine.usage.toList(res) }
-
-        try {
-            machine.run(SimFlopsWorkload(2_000, utilization = 1.0))
-            yield()
-            job.cancel()
-            assertEquals(listOf(0.0, 1.0, 0.0), res) { "Machine is fully utilized" }
-        } finally {
-            machine.close()
-        }
-    }
-
-    @Test
-    fun testSpeed() = runBlockingSimulation {
-        val machine = SimBareMetalMachine(
-            SimResourceInterpreter(coroutineContext, clock),
-            machineModel,
-            SimplePowerDriver(ConstantPowerModel(0.0))
-        )
-
-        try {
-            coroutineScope {
-                launch { machine.run(SimFlopsWorkload(2_000, utilization = 1.0)) }
-                assertArrayEquals(doubleArrayOf(1000.0, 1000.0), machine.speed)
-            }
-        } finally {
-            machine.close()
-        }
-    }
-
-    @Test
     fun testPower() = runBlockingSimulation {
         val interpreter = SimResourceInterpreter(coroutineContext, clock)
         val machine = SimBareMetalMachine(
diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorTest.kt
index 918271d1..8dea0045 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimHypervisorTest.kt
@@ -22,11 +22,7 @@
 
 package org.opendc.simulator.compute.kernel
 
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.coroutineScope
-import kotlinx.coroutines.flow.toList
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.yield
+import kotlinx.coroutines.*
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
@@ -108,19 +104,14 @@ internal class SimHypervisorTest {
         }
         yield()
         val vm = hypervisor.createMachine(model)
-        val res = mutableListOf<Double>()
-        val job = launch { machine.usage.toList(res) }
-
         vm.run(workloadA)
         yield()
-        job.cancel()
         machine.close()
 
         assertAll(
             { assertEquals(1113300.0, listener.totalRequestedWork, "Requested Burst does not match") },
             { assertEquals(1023300.0, listener.totalGrantedWork, "Granted Burst does not match") },
             { assertEquals(90000.0, listener.totalOvercommittedWork, "Overcommissioned Burst does not match") },
-            { assertEquals(listOf(0.0, 0.00875, 1.0, 0.0, 0.0571875, 0.0), res) { "VM usage is correct" } },
             { assertEquals(1200000, clock.millis()) { "Current time is correct" } }
         )
     }
diff --git a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorTest.kt b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorTest.kt
index 80496992..3d3feb2a 100644
--- a/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorTest.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/test/kotlin/org/opendc/simulator/compute/kernel/SimSpaceSharedHypervisorTest.kt
@@ -23,7 +23,6 @@
 package org.opendc.simulator.compute.kernel
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.toList
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.yield
 import org.junit.jupiter.api.Assertions.*
@@ -64,9 +63,6 @@ internal class SimSpaceSharedHypervisorTest {
      */
     @Test
     fun testTrace() = runBlockingSimulation {
-        val usagePm = mutableListOf<Double>()
-        val usageVm = mutableListOf<Double>()
-
         val duration = 5 * 60L
         val workloadA =
             SimTraceWorkload(
@@ -84,27 +80,15 @@ internal class SimSpaceSharedHypervisorTest {
         )
         val hypervisor = SimSpaceSharedHypervisor(interpreter)
 
-        val colA = launch { machine.usage.toList(usagePm) }
         launch { machine.run(hypervisor) }
-
-        yield()
-
         val vm = hypervisor.createMachine(machineModel)
-        val colB = launch { vm.usage.toList(usageVm) }
         vm.run(workloadA)
         yield()
 
         vm.close()
         machine.close()
-        colA.cancel()
-        colB.cancel()
 
-        assertAll(
-            { assertEquals(listOf(0.0, 0.00875, 1.0, 0.0, 0.0571875, 0.0), usagePm) { "Correct PM usage" } },
-            // Temporary limitation is that VMs do not emit usage information
-            // { assertEquals(listOf(0.0, 0.00875, 1.0, 0.0, 0.0571875, 0.0), usageVm) { "Correct VM usage" } },
-            { assertEquals(5 * 60L * 4000, clock.millis()) { "Took enough time" } }
-        )
+        assertEquals(5 * 60L * 4000, clock.millis()) { "Took enough time" }
     }
 
     /**