simulator: Add Linux CPU frequency scaling governors

This change adds the CPU frequency scaling governors that are found in
the Linux kernel, which include the conservative and on-demand governor.

9 files changed, 231 insertions, 16 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractHypervisor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractHypervisor.kt
index 57c25b86..d24ed1f3 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractHypervisor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/SimAbstractHypervisor.kt
@@ -23,6 +23,7 @@
 package org.opendc.simulator.compute
 
 import org.opendc.simulator.compute.cpufreq.ScalingGovernor
+import org.opendc.simulator.compute.cpufreq.ScalingPolicy
 import org.opendc.simulator.compute.interference.PerformanceInterferenceModel
 import org.opendc.simulator.compute.model.ProcessingUnit
 import org.opendc.simulator.resources.*
@@ -100,11 +101,12 @@ public abstract class SimAbstractHypervisor(
         switch = createSwitch(ctx)
 
         for (cpu in ctx.cpus) {
-            val governor = scalingGovernor?.createLogic(cpu)
+            val governor = scalingGovernor?.createLogic(ScalingPolicyImpl(cpu))
             if (governor != null) {
                 governors.add(governor)
                 governor.onStart()
             }
+
             switch.addInput(cpu)
         }
     }
@@ -146,4 +148,19 @@ public abstract class SimAbstractHypervisor(
 
         override fun toString(): String = "SimAbstractHypervisor.VCpu[model=$model]"
     }
+
+    /**
+     * A [ScalingPolicy] for a physical CPU of the hypervisor.
+     */
+    private class ScalingPolicyImpl(override val cpu: SimProcessingUnit) : ScalingPolicy {
+        override var target: Double
+            get() = cpu.capacity
+            set(value) {
+                cpu.capacity = value
+            }
+
+        override val max: Double = cpu.model.frequency
+
+        override val min: Double = 0.0
+    }
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ConservativeScalingGovernor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ConservativeScalingGovernor.kt
new file mode 100644
index 00000000..562c0b73
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ConservativeScalingGovernor.kt
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2021 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.cpufreq
+
+/**
+ * A CPUFreq [ScalingGovernor] that models the conservative scaling governor in the Linux kernel.
+ */
+public class ConservativeScalingGovernor(public val threshold: Double = 0.8, private val stepSize: Double = -1.0) : ScalingGovernor {
+    override fun createLogic(policy: ScalingPolicy): ScalingGovernor.Logic = object : ScalingGovernor.Logic {
+        /**
+         * The step size to use.
+         */
+        private val stepSize = if (this@ConservativeScalingGovernor.stepSize < 0) {
+            // https://github.com/torvalds/linux/blob/master/drivers/cpufreq/cpufreq_conservative.c#L33
+            policy.max * 0.05
+        } else {
+            this@ConservativeScalingGovernor.stepSize.coerceAtMost(policy.max)
+        }
+
+        /**
+         * The previous load of the CPU.
+         */
+        private var previousLoad = threshold
+
+        override fun onStart() {
+            policy.target = policy.min
+        }
+
+        override fun onLimit(load: Double) {
+            val currentTarget = policy.target
+            if (load > threshold) {
+                // Check for load increase (see: https://github.com/torvalds/linux/blob/master/drivers/cpufreq/cpufreq_conservative.c#L102)
+                val step = when {
+                    load > previousLoad -> stepSize
+                    load < previousLoad -> -stepSize
+                    else -> 0.0
+                }
+                policy.target = (currentTarget + step).coerceIn(policy.min, policy.max)
+            }
+            previousLoad = load
+        }
+    }
+
+    override fun toString(): String = "ConservativeScalingGovernor[threshold=$threshold,stepSize=$stepSize]"
+}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/OnDemandScalingGovernor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/OnDemandScalingGovernor.kt
new file mode 100644
index 00000000..2c4a83f1
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/OnDemandScalingGovernor.kt
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2021 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.cpufreq
+
+/**
+ * A CPUFreq [ScalingGovernor] that models the on-demand scaling governor in the Linux kernel.
+ */
+public class OnDemandScalingGovernor(public val threshold: Double = 0.8) : ScalingGovernor {
+    override fun createLogic(policy: ScalingPolicy): ScalingGovernor.Logic = object : ScalingGovernor.Logic {
+        /**
+         * The multiplier used for the linear frequency scaling.
+         */
+        private val multiplier = (policy.max - policy.min) / 100
+
+        override fun onStart() {
+            policy.target = policy.min
+        }
+
+        override fun onLimit(load: Double) {
+            policy.target = if (load < threshold) {
+                /* Proportional scaling (see: https://github.com/torvalds/linux/blob/master/drivers/cpufreq/cpufreq_ondemand.c#L151). */
+                policy.min + load * multiplier
+            } else {
+                policy.max
+            }
+        }
+    }
+
+    override fun toString(): String = "OnDemandScalingGovernor[threshold=$threshold]"
+}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PerformanceScalingGovernor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PerformanceScalingGovernor.kt
index 245877be..8b1d49f6 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PerformanceScalingGovernor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PerformanceScalingGovernor.kt
@@ -22,17 +22,15 @@
 
 package org.opendc.simulator.compute.cpufreq
 
-import org.opendc.simulator.compute.SimProcessingUnit
-
 /**
  * A CPUFreq [ScalingGovernor] that causes the highest possible frequency to be requested from the resource.
  */
 public class PerformanceScalingGovernor : ScalingGovernor {
-    override fun createLogic(cpu: SimProcessingUnit): ScalingGovernor.Logic = object : ScalingGovernor.Logic {
+    override fun createLogic(policy: ScalingPolicy): ScalingGovernor.Logic = object : ScalingGovernor.Logic {
         override fun onStart() {
-            cpu.capacity = cpu.model.frequency
+            policy.target = policy.max
         }
-
-        override fun toString(): String = "PerformanceScalingGovernor.Logic"
     }
+
+    override fun toString(): String = "PerformanceScalingGovernor"
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PowerSaveScalingGovernor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PowerSaveScalingGovernor.kt
new file mode 100644
index 00000000..0889980c
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/PowerSaveScalingGovernor.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021 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.cpufreq
+
+/**
+ * A CPUFreq [ScalingGovernor] that causes the lowest possible frequency to be requested from the resource.
+ */
+public class PowerSaveScalingGovernor : ScalingGovernor {
+    override fun createLogic(policy: ScalingPolicy): ScalingGovernor.Logic = object : ScalingGovernor.Logic {
+        override fun onStart() {
+            policy.target = policy.min
+        }
+    }
+
+    override fun toString(): String = "PowerSaveScalingGovernor"
+}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingGovernor.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingGovernor.kt
index b7e7ffc6..3fb93ad9 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingGovernor.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingGovernor.kt
@@ -22,8 +22,6 @@
 
 package org.opendc.simulator.compute.cpufreq
 
-import org.opendc.simulator.compute.SimProcessingUnit
-
 /**
  * A [ScalingGovernor] in the CPUFreq subsystem of OpenDC is responsible for scaling the frequency of simulated CPUs
  * independent of the particular implementation of the CPU.
@@ -35,9 +33,9 @@ import org.opendc.simulator.compute.SimProcessingUnit
  */
 public interface ScalingGovernor {
     /**
-     * Create the scaling logic for the specified [cpu]
+     * Create the scaling logic for the specified [policy]
      */
-    public fun createLogic(cpu: SimProcessingUnit): Logic
+    public fun createLogic(policy: ScalingPolicy): Logic
 
     /**
      * The logic of the scaling governor.
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingPolicy.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingPolicy.kt
new file mode 100644
index 00000000..0552d279
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/cpufreq/ScalingPolicy.kt
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2021 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.cpufreq
+
+import org.opendc.simulator.compute.SimProcessingUnit
+
+/**
+ * An interface that holds the state managed by a [ScalingGovernor] and used by the underlying machine to control the
+ * CPU frequencies.
+ */
+public interface ScalingPolicy {
+    /**
+     * The processing unit that is associated with this policy.
+     */
+    public val cpu: SimProcessingUnit
+
+    /**
+     * The target frequency which the CPU should attempt to attain.
+     */
+    public var target: Double
+
+    /**
+     * The minimum frequency to which the CPU may scale.
+     */
+    public val min: Double
+
+    /**
+     * The maximum frequency to which the CPU may scale.
+     */
+    public val max: Double
+}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/PStatePowerDriver.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/PStatePowerDriver.kt
index 6328c8e4..6577fbfc 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/PStatePowerDriver.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/PStatePowerDriver.kt
@@ -37,7 +37,7 @@ public class PStatePowerDriver(states: Map<Double, PowerModel>) : PowerDriver {
     /**
      * The P-States defined by the user and ordered by key.
      */
-    private val states = TreeMap(states)
+    private val states: TreeMap<Double, PowerModel> = TreeMap(states)
 
     override fun createLogic(machine: SimMachine, cpus: List<SimProcessingUnit>): PowerDriver.Logic = object : PowerDriver.Logic {
         override fun computePower(): Double {
@@ -54,7 +54,7 @@ public class PStatePowerDriver(states: Map<Double, PowerModel>) : PowerDriver {
             val utilization = totalSpeed / (actualFreq * cpus.size)
             return model.computePower(utilization)
         }
-
-        override fun toString(): String = "PStatePowerDriver.Logic"
     }
+
+    override fun toString(): String = "PStatePowerDriver[states=$states]"
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
index 5c5ceff5..e43c89ac 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
+++ b/opendc-simulator/opendc-simulator-compute/src/main/kotlin/org/opendc/simulator/compute/power/SimplePowerDriver.kt
@@ -33,7 +33,7 @@ public class SimplePowerDriver(private val model: PowerModel) : PowerDriver {
         override fun computePower(): Double {
             return model.computePower(machine.usage.value)
         }
-
-        override fun toString(): String = "SimplePowerDriver.Logic"
     }
+
+    override fun toString(): String = "SimplePowerDriver[model=$model]"
 }