All simulation are now run with a single CPU and single MemoryUnit. multi CPUs are combined into one. This is for performance and explainability. (#255)

16 files changed, 315 insertions, 537 deletions

diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimAbstractMachine.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimAbstractMachine.java
index af56f248..3a9e35c1 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimAbstractMachine.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimAbstractMachine.java
@@ -23,7 +23,6 @@
 package org.opendc.simulator.compute;
 
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
 import org.opendc.simulator.compute.device.SimNetworkAdapter;
@@ -43,7 +42,7 @@ import org.opendc.simulator.flow2.util.FlowTransforms;
 public abstract class SimAbstractMachine implements SimMachine {
     private final MachineModel model;
 
-    private Context activeContext;
+    private SimAbstractMachineContext activeContext;
 
     /**
      * Construct a {@link SimAbstractMachine} instance.
@@ -66,40 +65,40 @@ public abstract class SimAbstractMachine implements SimMachine {
             throw new IllegalStateException("A machine cannot run multiple workloads concurrently");
         }
 
-        final Context ctx = createContext(workload, new HashMap<>(meta), completion);
+        final SimAbstractMachineContext ctx = createContext(workload, new HashMap<>(meta), completion);
         ctx.start();
         return ctx;
     }
 
     @Override
     public final void cancel() {
-        final Context context = activeContext;
+        final SimAbstractMachineContext context = activeContext;
         if (context != null) {
             context.shutdown();
         }
     }
 
     /**
-     * Construct a new {@link Context} instance representing the active execution.
+     * Construct a new {@link SimAbstractMachineContext} instance representing the active execution.
      *
      * @param workload   The workload to start on the machine.
      * @param meta       The metadata to pass to the workload.
      * @param completion A block that is invoked when the workload completes carrying an exception if thrown by the workload.
      */
-    protected abstract Context createContext(
+    protected abstract SimAbstractMachineContext createContext(
             SimWorkload workload, Map<String, Object> meta, Consumer<Exception> completion);
 
     /**
-     * Return the active {@link Context} instance (if any).
+     * Return the active {@link SimAbstractMachineContext} instance (if any).
      */
-    protected Context getActiveContext() {
+    protected SimAbstractMachineContext getActiveContext() {
         return activeContext;
     }
 
     /**
      * The execution context in which the workload runs.
      */
-    public abstract static class Context implements SimMachineContext {
+    public abstract static class SimAbstractMachineContext implements SimMachineContext {
         private final SimAbstractMachine machine;
         private final SimWorkload workload;
         private final Map<String, Object> meta;
@@ -108,14 +107,14 @@ public abstract class SimAbstractMachine implements SimMachine {
         private SimWorkload snapshot;
 
         /**
-         * Construct a new {@link Context} instance.
+         * Construct a new {@link SimAbstractMachineContext} instance.
          *
          * @param machine The {@link SimAbstractMachine} to which the context belongs.
          * @param workload The {@link SimWorkload} to which the context belongs.
          * @param meta The metadata passed to the context.
          * @param completion A block that is invoked when the workload completes carrying an exception if thrown by the workload.
          */
-        public Context(
+        public SimAbstractMachineContext(
                 SimAbstractMachine machine,
                 SimWorkload workload,
                 Map<String, Object> meta,
@@ -145,10 +144,8 @@ public abstract class SimAbstractMachine implements SimMachine {
         public void reset() {
             final FlowGraph graph = getMemory().getInput().getGraph();
 
-            for (SimProcessingUnit cpu : getCpus()) {
-                final Inlet inlet = cpu.getInput();
-                graph.disconnect(inlet);
-            }
+            final Inlet inlet = getCpu().getInput();
+            graph.disconnect(inlet);
 
             graph.disconnect(getMemory().getInput());
 
@@ -225,16 +222,12 @@ public abstract class SimAbstractMachine implements SimMachine {
      */
     public static final class Memory implements SimMemory {
         private final SimpleFlowSink sink;
-        private final List<MemoryUnit> models;
+        private final MemoryUnit memoryUnit;
 
-        public Memory(FlowGraph graph, List<MemoryUnit> models) {
-            long memorySize = 0;
-            for (MemoryUnit mem : models) {
-                memorySize += mem.getSize();
-            }
+        public Memory(FlowGraph graph, MemoryUnit memoryUnit) {
 
-            this.sink = new SimpleFlowSink(graph, (float) memorySize);
-            this.models = models;
+            this.memoryUnit = memoryUnit;
+            this.sink = new SimpleFlowSink(graph, (float) memoryUnit.getSize());
         }
 
         @Override
@@ -243,8 +236,8 @@ public abstract class SimAbstractMachine implements SimMachine {
         }
 
         @Override
-        public List<MemoryUnit> getModels() {
-            return models;
+        public MemoryUnit getMemoryUnit() {
+            return memoryUnit;
         }
 
         @Override
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimBareMetalMachine.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimBareMetalMachine.java
index 11356eb2..6acc605e 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimBareMetalMachine.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimBareMetalMachine.java
@@ -28,8 +28,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
 import org.opendc.simulator.compute.device.SimPeripheral;
+import org.opendc.simulator.compute.model.Cpu;
 import org.opendc.simulator.compute.model.MachineModel;
-import org.opendc.simulator.compute.model.ProcessingUnit;
 import org.opendc.simulator.compute.workload.SimWorkload;
 import org.opendc.simulator.flow2.FlowGraph;
 import org.opendc.simulator.flow2.InPort;
@@ -56,7 +56,7 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
     /**
      * The resources of this machine.
      */
-    private final List<Cpu> cpus;
+    private final SimCpu cpu;
 
     private final Memory memory;
     private final List<NetworkAdapter> net;
@@ -75,13 +75,7 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
         this.graph = graph;
         this.psu = psuFactory.newPsu(this, graph);
 
-        int cpuIndex = 0;
-        final ArrayList<Cpu> cpus = new ArrayList<>();
-        this.cpus = cpus;
-        for (ProcessingUnit cpu : model.getCpus()) {
-            cpus.add(new Cpu(psu, cpu, cpuIndex++));
-        }
-
+        this.cpu = new SimCpu(psu, model.getCpu(), 0);
         this.memory = new Memory(graph, model.getMemory());
 
         int netIndex = 0;
@@ -139,76 +133,58 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
      * Return the CPU capacity of the machine in MHz.
      */
     public double getCpuCapacity() {
-        final Context context = (Context) getActiveContext();
+        final SimAbstractMachineContext context = (SimAbstractMachineContext) getActiveContext();
 
         if (context == null) {
             return 0.0;
         }
 
-        float capacity = 0.f;
-
-        for (SimProcessingUnit cpu : context.cpus) {
-            capacity += cpu.getFrequency();
-        }
-
-        return capacity;
+        return cpu.getFrequency();
     }
 
     /**
      * The CPU demand of the machine in MHz.
      */
     public double getCpuDemand() {
-        final Context context = (Context) getActiveContext();
+        final SimAbstractMachineContext context = (SimAbstractMachineContext) getActiveContext();
 
         if (context == null) {
             return 0.0;
         }
 
-        float demand = 0.f;
-
-        for (SimProcessingUnit cpu : context.cpus) {
-            demand += cpu.getDemand();
-        }
-
-        return demand;
+        return cpu.getDemand();
     }
 
     /**
      * The CPU usage of the machine in MHz.
      */
     public double getCpuUsage() {
-        final Context context = (Context) getActiveContext();
+        final SimAbstractMachineContext context = (SimAbstractMachineContext) getActiveContext();
 
         if (context == null) {
             return 0.0;
         }
 
-        float rate = 0.f;
-
-        for (SimProcessingUnit cpu : context.cpus) {
-            rate += cpu.getSpeed();
-        }
-
-        return rate;
+        return cpu.getSpeed();
     }
 
     @Override
-    protected SimAbstractMachine.Context createContext(
+    protected SimAbstractMachine.SimAbstractMachineContext createContext(
             SimWorkload workload, Map<String, Object> meta, Consumer<Exception> completion) {
-        return new Context(this, workload, meta, completion);
+        return new SimAbstractMachineContext(this, workload, meta, completion);
     }
 
     /**
      * The execution context for a {@link SimBareMetalMachine}.
      */
-    private static final class Context extends SimAbstractMachine.Context {
+    private static final class SimAbstractMachineContext extends SimAbstractMachine.SimAbstractMachineContext {
         private final FlowGraph graph;
-        private final List<Cpu> cpus;
+        private final SimCpu cpu;
         private final Memory memory;
         private final List<NetworkAdapter> net;
         private final List<StorageDevice> disk;
 
-        private Context(
+        private SimAbstractMachineContext(
                 SimBareMetalMachine machine,
                 SimWorkload workload,
                 Map<String, Object> meta,
@@ -216,7 +192,7 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
             super(machine, workload, meta, completion);
 
             this.graph = machine.graph;
-            this.cpus = machine.cpus;
+            this.cpu = machine.cpu;
             this.memory = machine.memory;
             this.net = machine.net;
             this.disk = machine.disk;
@@ -228,8 +204,8 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
         }
 
         @Override
-        public List<? extends SimProcessingUnit> getCpus() {
-            return cpus;
+        public SimCpu getCpu() {
+            return cpu;
         }
 
         @Override
@@ -251,17 +227,17 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
     /**
      * A {@link SimProcessingUnit} of a bare-metal machine.
      */
-    private static final class Cpu implements SimProcessingUnit {
+    private static final class SimCpu implements SimProcessingUnit {
         private final SimPsu psu;
-        private final ProcessingUnit model;
+        private final Cpu cpuModel;
         private final InPort port;
 
-        private Cpu(SimPsu psu, ProcessingUnit model, int id) {
+        private SimCpu(SimPsu psu, Cpu cpuModel, int id) {
             this.psu = psu;
-            this.model = model;
-            this.port = psu.getCpuPower(id, model);
+            this.cpuModel = cpuModel;
+            this.port = psu.getCpuPower(id, cpuModel);
 
-            this.port.pull((float) model.getFrequency());
+            this.port.pull((float) cpuModel.getTotalCapacity());
         }
 
         @Override
@@ -272,7 +248,7 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
         @Override
         public void setFrequency(double frequency) {
             // Clamp the capacity of the CPU between [0.0, maxFreq]
-            frequency = Math.max(0, Math.min(model.getFrequency(), frequency));
+            frequency = Math.max(0, Math.min(cpuModel.getTotalCapacity(), frequency));
             psu.setCpuFrequency(port, frequency);
         }
 
@@ -287,8 +263,8 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
         }
 
         @Override
-        public ProcessingUnit getModel() {
-            return model;
+        public org.opendc.simulator.compute.model.Cpu getCpuModel() {
+            return cpuModel;
         }
 
         @Override
@@ -298,7 +274,7 @@ public final class SimBareMetalMachine extends SimAbstractMachine {
 
         @Override
         public String toString() {
-            return "SimBareMetalMachine.Cpu[model=" + model + "]";
+            return "SimBareMetalMachine.Cpu[model=" + cpuModel + "]";
         }
     }
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMachineContext.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMachineContext.java
index 7f98dee5..887967fb 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMachineContext.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMachineContext.java
@@ -51,7 +51,7 @@ public interface SimMachineContext {
     /**
      * Return the CPUs available on the machine.
      */
-    List<? extends SimProcessingUnit> getCpus();
+    SimProcessingUnit getCpu();
 
     /**
      * Return the memory interface of the machine.
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMemory.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMemory.java
index 4fcc64ab..85027f28 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMemory.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimMemory.java
@@ -22,7 +22,6 @@
 
 package org.opendc.simulator.compute;
 
-import java.util.List;
 import org.opendc.simulator.compute.model.MemoryUnit;
 import org.opendc.simulator.flow2.sink.FlowSink;
 
@@ -38,5 +37,5 @@ public interface SimMemory extends FlowSink {
     /**
      * Return the models representing the static information of the memory units supporting this interface.
      */
-    List<MemoryUnit> getModels();
+    MemoryUnit getMemoryUnit();
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimProcessingUnit.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimProcessingUnit.java
index 3dbd3656..213c3d4f 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimProcessingUnit.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimProcessingUnit.java
@@ -22,7 +22,7 @@
 
 package org.opendc.simulator.compute;
 
-import org.opendc.simulator.compute.model.ProcessingUnit;
+import org.opendc.simulator.compute.model.Cpu;
 import org.opendc.simulator.flow2.sink.FlowSink;
 
 /**
@@ -58,5 +58,5 @@ public interface SimProcessingUnit extends FlowSink {
     /**
      *  The model representing the static properties of the processing unit.
      */
-    ProcessingUnit getModel();
+    Cpu getCpuModel();
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsu.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsu.java
index 68dae4bf..e7718604 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsu.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsu.java
@@ -22,7 +22,7 @@
 
 package org.opendc.simulator.compute;
 
-import org.opendc.simulator.compute.model.ProcessingUnit;
+import org.opendc.simulator.compute.model.Cpu;
 import org.opendc.simulator.flow2.InPort;
 import org.opendc.simulator.power.SimPowerInlet;
 
@@ -57,7 +57,7 @@ public abstract class SimPsu extends SimPowerInlet {
      * @param id The unique identifier of the CPU for this machine.
      * @param model The details of the processing unit.
      */
-    abstract InPort getCpuPower(int id, ProcessingUnit model);
+    abstract InPort getCpuPower(int id, Cpu model);
 
     /**
      * This method is invoked when the CPU frequency is changed for the specified <code>port</code>.
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsuFactories.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsuFactories.java
index 5b118429..27327616 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsuFactories.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/SimPsuFactories.java
@@ -24,7 +24,7 @@ package org.opendc.simulator.compute;
 
 import java.time.InstantSource;
 import org.jetbrains.annotations.NotNull;
-import org.opendc.simulator.compute.model.ProcessingUnit;
+import org.opendc.simulator.compute.model.Cpu;
 import org.opendc.simulator.compute.power.CpuPowerModel;
 import org.opendc.simulator.flow2.FlowGraph;
 import org.opendc.simulator.flow2.FlowStage;
@@ -92,7 +92,7 @@ public class SimPsuFactories {
         }
 
         @Override
-        InPort getCpuPower(int id, ProcessingUnit model) {
+        InPort getCpuPower(int id, Cpu model) {
             final InPort port = stage.getInlet("cpu" + id);
             port.setMask(true);
             return port;
@@ -165,8 +165,8 @@ public class SimPsuFactories {
         }
 
         @Override
-        InPort getCpuPower(int id, ProcessingUnit model) {
-            targetFreq += model.getFrequency();
+        InPort getCpuPower(int id, Cpu model) {
+            targetFreq += model.getTotalCapacity();
 
             final InPort port = stage.getInlet("cpu" + id);
             port.setHandler(handler);
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimHypervisor.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimHypervisor.java
index aced54a7..42750b0f 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimHypervisor.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimHypervisor.java
@@ -29,7 +29,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.SplittableRandom;
 import java.util.function.Consumer;
-import java.util.stream.Collectors;
 import org.opendc.simulator.compute.SimAbstractMachine;
 import org.opendc.simulator.compute.SimMachine;
 import org.opendc.simulator.compute.SimMachineContext;
@@ -44,8 +43,8 @@ import org.opendc.simulator.compute.kernel.cpufreq.ScalingPolicy;
 import org.opendc.simulator.compute.kernel.interference.VmInterferenceDomain;
 import org.opendc.simulator.compute.kernel.interference.VmInterferenceMember;
 import org.opendc.simulator.compute.kernel.interference.VmInterferenceProfile;
+import org.opendc.simulator.compute.model.Cpu;
 import org.opendc.simulator.compute.model.MachineModel;
-import org.opendc.simulator.compute.model.ProcessingUnit;
 import org.opendc.simulator.compute.workload.SimWorkload;
 import org.opendc.simulator.flow2.FlowGraph;
 import org.opendc.simulator.flow2.FlowStage;
@@ -68,8 +67,8 @@ public final class SimHypervisor implements SimWorkload {
     private final ScalingGovernorFactory scalingGovernorFactory;
     private final VmInterferenceDomain interferenceDomain;
 
-    private Context activeContext;
-    private final ArrayList<VirtualMachine> vms = new ArrayList<>();
+    private SimHyperVisorContext activeContext;
+    private final ArrayList<SimVirtualMachine> vms = new ArrayList<>();
     private final HvCounters counters = new HvCounters();
 
     @Override
@@ -156,7 +155,7 @@ public final class SimHypervisor implements SimWorkload {
             throw new IllegalArgumentException("Machine does not fit");
         }
 
-        VirtualMachine vm = new VirtualMachine(model);
+        SimVirtualMachine vm = new SimVirtualMachine(model);
         vms.add(vm);
         return vm;
     }
@@ -169,7 +168,7 @@ public final class SimHypervisor implements SimWorkload {
     public void removeMachine(SimVirtualMachine machine) {
         if (vms.remove(machine)) {
             // This cast must always succeed, since `_vms` only contains `VirtualMachine` types.
-            ((VirtualMachine) machine).close();
+            ((SimVirtualMachine) machine).close();
         }
     }
 
@@ -177,7 +176,7 @@ public final class SimHypervisor implements SimWorkload {
      * Return the CPU capacity of the hypervisor in MHz.
      */
     public double getCpuCapacity() {
-        final Context context = activeContext;
+        final SimHyperVisorContext context = activeContext;
 
         if (context == null) {
             return 0.0;
@@ -190,7 +189,7 @@ public final class SimHypervisor implements SimWorkload {
      * The CPU demand of the hypervisor in MHz.
      */
     public double getCpuDemand() {
-        final Context context = activeContext;
+        final SimHyperVisorContext context = activeContext;
 
         if (context == null) {
             return 0.0;
@@ -203,7 +202,7 @@ public final class SimHypervisor implements SimWorkload {
      * The CPU usage of the hypervisor in MHz.
      */
     public double getCpuUsage() {
-        final Context context = activeContext;
+        final SimHyperVisorContext context = activeContext;
 
         if (context == null) {
             return 0.0;
@@ -217,26 +216,26 @@ public final class SimHypervisor implements SimWorkload {
      * moment.
      */
     public boolean canFit(MachineModel model) {
-        final Context context = activeContext;
+        final SimHyperVisorContext context = activeContext;
         if (context == null) {
             return false;
         }
 
         final FlowMultiplexer multiplexer = context.multiplexer;
-        return (multiplexer.getMaxInputs() - multiplexer.getInputCount())
-                >= model.getCpus().size();
+        return (multiplexer.getMaxInputs() - multiplexer.getInputCount()) >= 1;
     }
 
     @Override
     public void onStart(SimMachineContext ctx) {
-        final Context context = new Context(ctx, muxFactory, scalingGovernorFactory, counters);
+        final SimHyperVisorContext context =
+                new SimHyperVisorContext(ctx, muxFactory, scalingGovernorFactory, counters);
         context.start();
         activeContext = context;
     }
 
     @Override
     public void onStop(SimMachineContext ctx) {
-        final Context context = activeContext;
+        final SimHyperVisorContext context = activeContext;
         if (context != null) {
             activeContext = null;
             context.stop();
@@ -276,11 +275,11 @@ public final class SimHypervisor implements SimWorkload {
     /**
      * The context which carries the state when the hypervisor is running on a machine.
      */
-    private static final class Context implements FlowStageLogic {
+    private static final class SimHyperVisorContext implements FlowStageLogic {
         private final SimMachineContext ctx;
         private final FlowMultiplexer multiplexer;
         private final FlowStage stage;
-        private final List<ScalingGovernor> scalingGovernors;
+        private final ScalingGovernor scalingGovernor;
         private final InstantSource clock;
         private final HvCounters counters;
 
@@ -290,7 +289,7 @@ public final class SimHypervisor implements SimWorkload {
         private float previousRate;
         private float previousCapacity;
 
-        private Context(
+        private SimHyperVisorContext(
                 SimMachineContext ctx,
                 FlowMultiplexerFactory muxFactory,
                 ScalingGovernorFactory scalingGovernorFactory,
@@ -306,20 +305,15 @@ public final class SimHypervisor implements SimWorkload {
 
             this.lastCounterUpdate = clock.millis();
 
+            final SimProcessingUnit cpu = ctx.getCpu();
+
             if (scalingGovernorFactory != null) {
-                this.scalingGovernors = ctx.getCpus().stream()
-                        .map(cpu -> scalingGovernorFactory.newGovernor(new ScalingPolicyImpl(cpu)))
-                        .collect(Collectors.toList());
+                this.scalingGovernor = scalingGovernorFactory.newGovernor(new ScalingPolicyImpl(cpu));
             } else {
-                this.scalingGovernors = Collections.emptyList();
+                this.scalingGovernor = null;
             }
 
-            float cpuCapacity = 0.f;
-            final List<? extends SimProcessingUnit> cpus = ctx.getCpus();
-            for (SimProcessingUnit cpu : cpus) {
-                cpuCapacity += cpu.getFrequency();
-            }
-            this.d = cpus.size() / cpuCapacity;
+            this.d = 1 / cpu.getFrequency();
         }
 
         /**
@@ -329,12 +323,10 @@ public final class SimHypervisor implements SimWorkload {
             final FlowGraph graph = ctx.getGraph();
             final FlowMultiplexer multiplexer = this.multiplexer;
 
-            for (SimProcessingUnit cpu : ctx.getCpus()) {
-                graph.connect(multiplexer.newOutput(), cpu.getInput());
-            }
+            graph.connect(multiplexer.newOutput(), ctx.getCpu().getInput());
 
-            for (ScalingGovernor governor : scalingGovernors) {
-                governor.onStart();
+            if (this.scalingGovernor != null) {
+                this.scalingGovernor.onStart();
             }
         }
 
@@ -392,7 +384,7 @@ public final class SimHypervisor implements SimWorkload {
             updateCounters(now);
 
             final FlowMultiplexer multiplexer = this.multiplexer;
-            final List<ScalingGovernor> scalingGovernors = this.scalingGovernors;
+            final ScalingGovernor scalingGovernors = this.scalingGovernor;
 
             float demand = multiplexer.getDemand();
             float rate = multiplexer.getRate();
@@ -404,10 +396,8 @@ public final class SimHypervisor implements SimWorkload {
 
             double load = rate / Math.min(1.0, capacity);
 
-            if (!scalingGovernors.isEmpty()) {
-                for (ScalingGovernor governor : scalingGovernors) {
-                    governor.onLimit(load);
-                }
+            if (scalingGovernor != null) {
+                scalingGovernor.onLimit(load);
             }
 
             return Long.MAX_VALUE;
@@ -446,27 +436,25 @@ public final class SimHypervisor implements SimWorkload {
 
         @Override
         public double getMax() {
-            return cpu.getModel().getFrequency();
+            return cpu.getCpuModel().getTotalCapacity();
         }
     }
 
     /**
      * A virtual machine running on the hypervisor.
      */
-    private class VirtualMachine extends SimAbstractMachine implements SimVirtualMachine {
+    public class SimVirtualMachine extends SimAbstractMachine {
         private boolean isClosed;
         private final VmCounters counters = new VmCounters(this);
 
-        private VirtualMachine(MachineModel model) {
+        private SimVirtualMachine(MachineModel model) {
             super(model);
         }
 
-        @Override
         public SimHypervisorCounters getCounters() {
             return counters;
         }
 
-        @Override
         public double getCpuDemand() {
             final VmContext context = (VmContext) getActiveContext();
 
@@ -477,7 +465,6 @@ public final class SimHypervisor implements SimWorkload {
             return context.previousDemand;
         }
 
-        @Override
         public double getCpuUsage() {
             final VmContext context = (VmContext) getActiveContext();
 
@@ -488,7 +475,6 @@ public final class SimHypervisor implements SimWorkload {
             return context.usage;
         }
 
-        @Override
         public double getCpuCapacity() {
             final VmContext context = (VmContext) getActiveContext();
 
@@ -505,13 +491,13 @@ public final class SimHypervisor implements SimWorkload {
         }
 
         @Override
-        protected Context createContext(
+        protected SimAbstractMachineContext createContext(
                 SimWorkload workload, Map<String, Object> meta, Consumer<Exception> completion) {
             if (isClosed) {
                 throw new IllegalStateException("Virtual machine does not exist anymore");
             }
 
-            final SimHypervisor.Context context = activeContext;
+            final SimHyperVisorContext context = activeContext;
             if (context == null) {
                 throw new IllegalStateException("Hypervisor is inactive");
             }
@@ -529,7 +515,7 @@ public final class SimHypervisor implements SimWorkload {
         }
 
         @Override
-        public Context getActiveContext() {
+        public SimAbstractMachineContext getActiveContext() {
             return super.getActiveContext();
         }
 
@@ -544,10 +530,11 @@ public final class SimHypervisor implements SimWorkload {
     }
 
     /**
-     * A {@link SimAbstractMachine.Context} for a virtual machine instance.
+     * A {@link SimAbstractMachine.SimAbstractMachineContext} for a virtual machine instance.
      */
-    private static final class VmContext extends SimAbstractMachine.Context implements FlowStageLogic {
-        private final Context context;
+    private static final class VmContext extends SimAbstractMachine.SimAbstractMachineContext
+            implements FlowStageLogic {
+        private final SimHyperVisorContext simHyperVisorContext;
         private final SplittableRandom random;
         private final VmCounters vmCounters;
         private final HvCounters hvCounters;
@@ -556,7 +543,7 @@ public final class SimHypervisor implements SimWorkload {
         private final FlowMultiplexer multiplexer;
         private final InstantSource clock;
 
-        private final List<VCpu> cpus;
+        private final VCpu cpu;
         private final SimAbstractMachine.Memory memory;
         private final List<SimAbstractMachine.NetworkAdapter> net;
         private final List<SimAbstractMachine.StorageDevice> disk;
@@ -574,8 +561,8 @@ public final class SimHypervisor implements SimWorkload {
         private float previousCapacity;
 
         private VmContext(
-                Context context,
-                VirtualMachine machine,
+                SimHyperVisorContext simHyperVisorContext,
+                SimVirtualMachine machine,
                 SplittableRandom random,
                 VmInterferenceDomain interferenceDomain,
                 VmCounters vmCounters,
@@ -585,11 +572,11 @@ public final class SimHypervisor implements SimWorkload {
                 Consumer<Exception> completion) {
             super(machine, workload, meta, completion);
 
-            this.context = context;
+            this.simHyperVisorContext = simHyperVisorContext;
             this.random = random;
             this.vmCounters = vmCounters;
             this.hvCounters = hvCounters;
-            this.clock = context.clock;
+            this.clock = simHyperVisorContext.clock;
 
             final VmInterferenceProfile interferenceProfile = (VmInterferenceProfile) meta.get("interference-profile");
             VmInterferenceMember interferenceMember = null;
@@ -599,45 +586,36 @@ public final class SimHypervisor implements SimWorkload {
             }
             this.interferenceMember = interferenceMember;
 
-            final FlowGraph graph = context.ctx.getGraph();
+            final FlowGraph graph = simHyperVisorContext.ctx.getGraph();
             final FlowStage stage = graph.newStage(this);
             this.stage = stage;
             this.lastUpdate = clock.millis();
             this.lastCounterUpdate = clock.millis();
 
-            final FlowMultiplexer multiplexer = context.multiplexer;
+            final FlowMultiplexer multiplexer = simHyperVisorContext.multiplexer;
             this.multiplexer = multiplexer;
 
             final MachineModel model = machine.getModel();
-            final List<ProcessingUnit> cpuModels = model.getCpus();
-            final Inlet[] muxInlets = new Inlet[cpuModels.size()];
-            final ArrayList<VCpu> cpus = new ArrayList<>();
+            final Cpu cpuModel = model.getCpu();
+            final Inlet[] muxInlets = new Inlet[1];
 
             this.muxInlets = muxInlets;
-            this.cpus = cpus;
-
-            float capacity = 0.f;
 
-            for (int i = 0; i < cpuModels.size(); i++) {
-                final Inlet muxInlet = multiplexer.newInput();
-                muxInlets[i] = muxInlet;
+            final Inlet muxInlet = multiplexer.newInput();
+            muxInlets[0] = muxInlet;
 
-                final InPort input = stage.getInlet("cpu" + i);
-                final OutPort output = stage.getOutlet("mux" + i);
+            final InPort input = stage.getInlet("cpu");
+            final OutPort output = stage.getOutlet("mux");
 
-                final Handler handler = new Handler(this, input, output);
-                input.setHandler(handler);
-                output.setHandler(handler);
+            final Handler handler = new Handler(this, input, output);
+            input.setHandler(handler);
+            output.setHandler(handler);
 
-                final ProcessingUnit cpuModel = cpuModels.get(i);
-                capacity += cpuModel.getFrequency();
+            this.cpu = new VCpu(cpuModel, input);
 
-                final VCpu cpu = new VCpu(cpuModel, input);
-                cpus.add(cpu);
+            graph.connect(output, muxInlet);
 
-                graph.connect(output, muxInlet);
-            }
-            this.d = cpuModels.size() / capacity;
+            this.d = 1 / cpuModel.getTotalCapacity();
 
             this.memory = new SimAbstractMachine.Memory(graph, model.getMemory());
 
@@ -664,7 +642,7 @@ public final class SimHypervisor implements SimWorkload {
         void updateCounters(long now) {
             long lastUpdate = this.lastCounterUpdate;
             this.lastCounterUpdate = now;
-            long delta = now - lastUpdate;
+            long delta = now - lastUpdate; // time between updates
 
             if (delta > 0) {
                 final VmCounters counters = this.vmCounters;
@@ -673,7 +651,7 @@ public final class SimHypervisor implements SimWorkload {
                 float rate = this.usage;
                 float capacity = this.previousCapacity;
 
-                final double factor = this.d * delta;
+                final double factor = this.d * delta; // time between divided by total capacity
                 final double active = rate * factor;
 
                 counters.cpuActiveTime += Math.round(active);
@@ -695,8 +673,8 @@ public final class SimHypervisor implements SimWorkload {
         }
 
         @Override
-        public List<? extends SimProcessingUnit> getCpus() {
-            return cpus;
+        public SimProcessingUnit getCpu() {
+            return cpu;
         }
 
         @Override
@@ -746,7 +724,7 @@ public final class SimHypervisor implements SimWorkload {
             }
 
             // Invalidate the FlowStage of the hypervisor to update its counters (via onUpdate)
-            context.invalidate();
+            simHyperVisorContext.invalidate();
 
             return Long.MAX_VALUE;
         }
@@ -776,14 +754,14 @@ public final class SimHypervisor implements SimWorkload {
      * A {@link SimProcessingUnit} of a virtual machine.
      */
     private static final class VCpu implements SimProcessingUnit {
-        private final ProcessingUnit model;
+        private final Cpu model;
         private final InPort input;
 
-        private VCpu(ProcessingUnit model, InPort input) {
+        private VCpu(Cpu model, InPort input) {
             this.model = model;
             this.input = input;
 
-            input.pull((float) model.getFrequency());
+            input.pull((float) model.getTotalCapacity());
         }
 
         @Override
@@ -807,7 +785,7 @@ public final class SimHypervisor implements SimWorkload {
         }
 
         @Override
-        public ProcessingUnit getModel() {
+        public Cpu getCpuModel() {
             return model;
         }
 
@@ -901,7 +879,7 @@ public final class SimHypervisor implements SimWorkload {
 
         @Override
         public void sync() {
-            final Context context = activeContext;
+            final SimHyperVisorContext context = activeContext;
 
             if (context != null) {
                 context.updateCounters();
@@ -913,13 +891,13 @@ public final class SimHypervisor implements SimWorkload {
      * Implementation of {@link SimHypervisorCounters} for the virtual machine.
      */
     private static class VmCounters implements SimHypervisorCounters {
-        private final VirtualMachine vm;
+        private final SimVirtualMachine vm;
         private long cpuActiveTime;
         private long cpuIdleTime;
         private long cpuStealTime;
         private long cpuLostTime;
 
-        private VmCounters(VirtualMachine vm) {
+        private VmCounters(SimVirtualMachine vm) {
             this.vm = vm;
         }
 
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimVirtualMachine.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimVirtualMachine.java
deleted file mode 100644
index fdf5e47f..00000000
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/kernel/SimVirtualMachine.java
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright (c) 2022 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.kernel;
-
-import org.opendc.simulator.compute.SimMachine;
-
-/**
- * A virtual {@link SimMachine} running on top of another {@link SimMachine}.
- */
-public interface SimVirtualMachine extends SimMachine {
-    /**
-     * Return the performance counters associated with the virtual machine.
-     */
-    SimHypervisorCounters getCounters();
-
-    /**
-     * Return the CPU usage of the VM in MHz.
-     */
-    double getCpuUsage();
-
-    /**
-     * Return the CPU usage of the VM in MHz.
-     */
-    double getCpuDemand();
-
-    /**
-     * Return the CPU capacity of the VM in MHz.
-     */
-    double getCpuCapacity();
-}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/Cpu.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/Cpu.java
new file mode 100644
index 00000000..c319ae1a
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/Cpu.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2022 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;
+
+import java.util.Objects;
+
+/**
+ * A single logical compute unit of processor node, either virtual or physical.
+ */
+public final class Cpu {
+    private final int id;
+    private final int coreCount;
+    private final double coreSpeed;
+    private final double totalCapacity;
+
+    private final String vendor;
+    private final String modelName;
+    private final String arch;
+
+    /**
+     * Construct a {@link Cpu} instance.
+     *
+     * @param id The identifier of the CPU core within the processing node.
+     * @param coreCount The number of cores present in the CPU
+     * @param coreSpeed The speed of a single core
+     * @param vendor The vendor of the CPU
+     * @param modelName The name of the CPU
+     * @param arch The architecture of the CPU
+     */
+    public Cpu(int id, int coreCount, double coreSpeed, String vendor, String modelName, String arch) {
+        this.id = id;
+        this.coreCount = coreCount;
+        this.coreSpeed = coreSpeed;
+        this.totalCapacity = coreSpeed * coreCount;
+        this.vendor = vendor;
+        this.modelName = modelName;
+        this.arch = arch;
+    }
+
+    public Cpu(int id, int coreCount, double coreSpeed) {
+        this(id, coreCount, coreSpeed, "unkown", "unkown", "unkown");
+    }
+
+    /**
+     * Return the identifier of the CPU core within the processing node.
+     */
+    public int getId() {
+        return id;
+    }
+
+    /**
+     * Return the number of logical CPUs in the processor node.
+     */
+    public int getCoreCount() {
+        return coreCount;
+    }
+
+    /**
+     * Return the clock rate of a single core of the CPU MHz.
+     */
+    public double getCoreSpeed() {
+        return coreSpeed;
+    }
+
+    /**
+     * Return the clock rate of the CPU in MHz.
+     */
+    public double getTotalCapacity() {
+        return totalCapacity;
+    }
+
+    /**
+     * Return the vendor of the storage device.
+     */
+    public String getVendor() {
+        return vendor;
+    }
+
+    /**
+     * Return the model name of the device.
+     */
+    public String getModelName() {
+        return modelName;
+    }
+
+    /**
+     * Return the micro-architecture of the processor node.
+     */
+    public String getArchitecture() {
+        return arch;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Cpu that = (Cpu) o;
+        return id == that.id
+                && Double.compare(that.totalCapacity, totalCapacity) == 0
+                && Double.compare(that.coreSpeed, coreSpeed) == 0
+                && Objects.equals(vendor, that.vendor)
+                && Objects.equals(modelName, that.modelName)
+                && Objects.equals(arch, that.arch);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, coreCount, coreSpeed, totalCapacity, vendor, modelName, arch);
+    }
+
+    @Override
+    public String toString() {
+        return "ProcessingUnit[" + "id= " + id + ", coreCount= " + coreCount + ", coreSpeed= " + coreSpeed
+                + ", frequency= " + totalCapacity + ", vendor= " + vendor + ", modelName= " + modelName + ", arch= "
+                + arch + "]";
+    }
+}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/MachineModel.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/MachineModel.java
index 2c625fce..e4019dac 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/MachineModel.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/MachineModel.java
@@ -31,29 +31,23 @@ import java.util.Objects;
  * A description of the physical or virtual machine on which a bootable image runs.
  */
 public final class MachineModel {
-    private final List<ProcessingUnit> cpus;
-    private final List<MemoryUnit> memory;
+    private final Cpu cpu;
+    private final MemoryUnit memory;
     private final List<NetworkAdapter> net;
     private final List<StorageDevice> storage;
 
     /**
      * Construct a {@link MachineModel} instance.
      *
-     * @param cpus The list of processing units available to the image.
+     * @param cpu The cpu available to the image.
      * @param memory The list of memory units available to the image.
      * @param net A list of network adapters available to the machine.
      * @param storage A list of storage devices available to the machine.
      */
-    public MachineModel(
-            Iterable<ProcessingUnit> cpus,
-            Iterable<MemoryUnit> memory,
-            Iterable<NetworkAdapter> net,
-            Iterable<StorageDevice> storage) {
-        this.cpus = new ArrayList<>();
-        cpus.forEach(this.cpus::add);
+    public MachineModel(Cpu cpu, MemoryUnit memory, Iterable<NetworkAdapter> net, Iterable<StorageDevice> storage) {
+        this.cpu = cpu;
 
-        this.memory = new ArrayList<>();
-        memory.forEach(this.memory::add);
+        this.memory = memory;
 
         this.net = new ArrayList<>();
         net.forEach(this.net::add);
@@ -62,54 +56,50 @@ public final class MachineModel {
         storage.forEach(this.storage::add);
     }
 
+    public MachineModel(Cpu cpu, MemoryUnit memory) {
+        this(cpu, memory, Collections.emptyList(), Collections.emptyList());
+    }
+
     /**
      * Construct a {@link MachineModel} instance.
+     * A list of the same cpus, are automatically converted to a single CPU with the number of cores of
+     * all cpus in the list combined.
      *
      * @param cpus The list of processing units available to the image.
      * @param memory The list of memory units available to the image.
      */
-    public MachineModel(Iterable<ProcessingUnit> cpus, Iterable<MemoryUnit> memory) {
-        this(cpus, memory, Collections.emptyList(), Collections.emptyList());
+    public MachineModel(
+            List<Cpu> cpus, MemoryUnit memory, Iterable<NetworkAdapter> net, Iterable<StorageDevice> storage) {
+
+        this(
+                new Cpu(
+                        cpus.get(0).getId(),
+                        cpus.get(0).getCoreCount() * cpus.size(),
+                        cpus.get(0).getCoreSpeed(),
+                        cpus.get(0).getVendor(),
+                        cpus.get(0).getModelName(),
+                        cpus.get(0).getArchitecture()),
+                memory,
+                net,
+                storage);
     }
 
-    /**
-     * Optimize the [MachineModel] by merging all resources of the same type into a single resource with the combined
-     * capacity. Such configurations can be simulated more efficiently by OpenDC.
-     */
-    public MachineModel optimize() {
-        ProcessingUnit originalCpu = cpus.get(0);
-
-        double freq = 0.0;
-        for (ProcessingUnit cpu : cpus) {
-            freq += cpu.getFrequency();
-        }
-
-        ProcessingNode originalNode = originalCpu.getNode();
-        ProcessingNode processingNode = new ProcessingNode(
-                originalNode.getVendor(), originalNode.getModelName(), originalNode.getArchitecture(), 1);
-        ProcessingUnit processingUnit = new ProcessingUnit(processingNode, originalCpu.getId(), freq);
-
-        long memorySize = 0;
-        for (MemoryUnit mem : memory) {
-            memorySize += mem.getSize();
-        }
-        MemoryUnit memoryUnit = new MemoryUnit("Generic", "Generic", 3200.0, memorySize);
-
-        return new MachineModel(List.of(processingUnit), List.of(memoryUnit));
+    public MachineModel(List<Cpu> cpus, MemoryUnit memory) {
+        this(cpus, memory, Collections.emptyList(), Collections.emptyList());
     }
 
     /**
      * Return the processing units of this machine.
      */
-    public List<ProcessingUnit> getCpus() {
-        return Collections.unmodifiableList(cpus);
+    public Cpu getCpu() {
+        return this.cpu;
     }
 
     /**
      * Return the memory units of this machine.
      */
-    public List<MemoryUnit> getMemory() {
-        return Collections.unmodifiableList(memory);
+    public MemoryUnit getMemory() {
+        return memory;
     }
 
     /**
@@ -131,7 +121,7 @@ public final class MachineModel {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         MachineModel that = (MachineModel) o;
-        return cpus.equals(that.cpus)
+        return cpu.equals(that.cpu)
                 && memory.equals(that.memory)
                 && net.equals(that.net)
                 && storage.equals(that.storage);
@@ -139,11 +129,11 @@ public final class MachineModel {
 
     @Override
     public int hashCode() {
-        return Objects.hash(cpus, memory, net, storage);
+        return Objects.hash(cpu, memory, net, storage);
     }
 
     @Override
     public String toString() {
-        return "MachineModel[cpus=" + cpus + ",memory=" + memory + ",net=" + net + ",storage=" + storage + "]";
+        return "MachineModel[cpus=" + cpu + ",memory=" + memory + ",net=" + net + ",storage=" + storage + "]";
     }
 }
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/ProcessingUnit.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/ProcessingUnit.java
deleted file mode 100644
index 0bead16a..00000000
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/model/ProcessingUnit.java
+++ /dev/null
@@ -1,86 +0,0 @@
-/*
- * Copyright (c) 2022 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;
-
-import java.util.Objects;
-
-/**
- * A single logical compute unit of processor node, either virtual or physical.
- */
-public final class ProcessingUnit {
-    private final ProcessingNode node;
-    private final int id;
-    private final double frequency;
-
-    /**
-     * Construct a {@link ProcessingUnit} instance.
-     *
-     * @param node The processing node containing the CPU core.
-     * @param id The identifier of the CPU core within the processing node.
-     * @param frequency The clock rate of the CPU in MHz.
-     */
-    public ProcessingUnit(ProcessingNode node, int id, double frequency) {
-        this.node = node;
-        this.id = id;
-        this.frequency = frequency * node.getCoreCount();
-    }
-
-    /**
-     * Return the processing node containing the CPU core.
-     */
-    public ProcessingNode getNode() {
-        return node;
-    }
-
-    /**
-     * Return the identifier of the CPU core within the processing node.
-     */
-    public int getId() {
-        return id;
-    }
-
-    /**
-     * Return the clock rate of the CPU in MHz.
-     */
-    public double getFrequency() {
-        return frequency;
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
-        ProcessingUnit that = (ProcessingUnit) o;
-        return id == that.id && Double.compare(that.frequency, frequency) == 0 && Objects.equals(node, that.node);
-    }
-
-    @Override
-    public int hashCode() {
-        return Objects.hash(node, id, frequency);
-    }
-
-    @Override
-    public String toString() {
-        return "ProcessingUnit[node=" + node + ",id=" + id + ",frequency=" + frequency + "]";
-    }
-}
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimChainWorkload.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimChainWorkload.java
index edf201a7..1dcb3674 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimChainWorkload.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimChainWorkload.java
@@ -41,7 +41,7 @@ final class SimChainWorkload implements SimWorkload {
     private final SimWorkload[] workloads;
     private int activeWorkloadIndex;
 
-    private Context activeContext;
+    private SimChainWorkloadContext activeContext;
 
     private long checkpointInterval = 0;
     private long checkpointDuration = 0;
@@ -108,7 +108,7 @@ final class SimChainWorkload implements SimWorkload {
             return;
         }
 
-        final Context context = new Context(ctx);
+        final SimChainWorkloadContext context = new SimChainWorkloadContext(ctx);
         activeContext = context;
 
         if (checkpointInterval > 0) {
@@ -128,7 +128,7 @@ final class SimChainWorkload implements SimWorkload {
             return;
         }
 
-        final Context context = activeContext;
+        final SimChainWorkloadContext context = activeContext;
         activeContext = null;
 
         if (this.checkpointModel != null) {
@@ -174,7 +174,7 @@ final class SimChainWorkload implements SimWorkload {
         private Boolean firstCheckPoint = true;
 
         CheckPointModel(
-                Context context,
+                SimChainWorkloadContext context,
                 SimChainWorkload workload,
                 long checkpointInterval,
                 long checkpointDuration,
@@ -228,11 +228,11 @@ final class SimChainWorkload implements SimWorkload {
     /**
      * A {@link SimMachineContext} that intercepts the shutdown calls.
      */
-    private class Context implements SimMachineContext {
+    private class SimChainWorkloadContext implements SimMachineContext {
         private final SimMachineContext ctx;
         private SimWorkload snapshot;
 
-        private Context(SimMachineContext ctx) {
+        private SimChainWorkloadContext(SimMachineContext ctx) {
             this.ctx = ctx;
         }
 
@@ -247,8 +247,8 @@ final class SimChainWorkload implements SimWorkload {
         }
 
         @Override
-        public List<? extends SimProcessingUnit> getCpus() {
-            return ctx.getCpus();
+        public SimProcessingUnit getCpu() {
+            return ctx.getCpu();
         }
 
         @Override
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimFlopsWorkload.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimFlopsWorkload.java
index 06fcb2bc..5311fa38 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimFlopsWorkload.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimFlopsWorkload.java
@@ -22,7 +22,6 @@
 
 package org.opendc.simulator.compute.workload;
 
-import java.util.List;
 import org.opendc.simulator.compute.SimMachineContext;
 import org.opendc.simulator.compute.SimProcessingUnit;
 import org.opendc.simulator.flow2.FlowGraph;
@@ -92,17 +91,14 @@ public class SimFlopsWorkload implements SimWorkload, FlowStageLogic {
         final FlowStage stage = graph.newStage(this);
         this.stage = stage;
 
-        final List<? extends SimProcessingUnit> cpus = ctx.getCpus();
-        final OutPort[] outputs = new OutPort[cpus.size()];
+        final SimProcessingUnit cpu = ctx.getCpu();
+        final OutPort[] outputs = new OutPort[1];
         this.outputs = outputs;
 
-        for (int i = 0; i < cpus.size(); i++) {
-            final SimProcessingUnit cpu = cpus.get(i);
-            final OutPort output = stage.getOutlet("cpu" + i);
+        final OutPort output = stage.getOutlet("cpu");
 
-            graph.connect(output, cpu.getInput());
-            outputs[i] = output;
-        }
+        graph.connect(output, cpu.getInput());
+        outputs[0] = output;
 
         this.remainingAmount = flops;
         this.lastUpdate = graph.getEngine().getClock().millis();
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimRuntimeWorkload.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimRuntimeWorkload.java
index 64b1a10b..be4cc2f5 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimRuntimeWorkload.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimRuntimeWorkload.java
@@ -22,7 +22,6 @@
 
 package org.opendc.simulator.compute.workload;
 
-import java.util.List;
 import org.opendc.simulator.compute.SimMachineContext;
 import org.opendc.simulator.compute.SimProcessingUnit;
 import org.opendc.simulator.flow2.FlowGraph;
@@ -122,17 +121,14 @@ public class SimRuntimeWorkload implements SimWorkload, FlowStageLogic {
         final FlowStage stage = graph.newStage(this);
         this.stage = stage;
 
-        final List<? extends SimProcessingUnit> cpus = ctx.getCpus();
-        final OutPort[] outputs = new OutPort[cpus.size()];
+        final OutPort[] outputs = new OutPort[1];
         this.outputs = outputs;
 
-        for (int i = 0; i < cpus.size(); i++) {
-            final SimProcessingUnit cpu = cpus.get(i);
-            final OutPort output = stage.getOutlet("cpu" + i);
+        final SimProcessingUnit cpu = ctx.getCpu();
+        final OutPort output = stage.getOutlet("cpu");
 
-            graph.connect(output, cpu.getInput());
-            outputs[i] = output;
-        }
+        graph.connect(output, cpu.getInput());
+        outputs[0] = output;
 
         this.remainingDuration = duration;
         this.lastUpdate = graph.getEngine().getClock().millis();
diff --git a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimTrace.java b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimTrace.java
index 384907b2..b8445a9c 100644
--- a/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimTrace.java
+++ b/opendc-simulator/opendc-simulator-compute/src/main/java/org/opendc/simulator/compute/workload/SimTrace.java
@@ -210,11 +210,7 @@ public final class SimTrace {
         @Override
         public void onStart(SimMachineContext ctx) {
             final WorkloadStageLogic logic;
-            if (ctx.getCpus().size() == 1) {
-                logic = new SingleWorkloadLogic(ctx, offset, fragments.iterator());
-            } else {
-                logic = new MultiWorkloadLogic(ctx, offset, fragments.iterator());
-            }
+            logic = new SingleWorkloadLogic(ctx, offset, fragments.iterator());
             this.logic = logic;
         }
 
@@ -325,11 +321,9 @@ public final class SimTrace {
             this.fragments = fragments;
 
             final FlowGraph graph = ctx.getGraph();
-            final List<? extends SimProcessingUnit> cpus = ctx.getCpus();
-
             stage = graph.newStage(this);
 
-            final SimProcessingUnit cpu = cpus.get(0);
+            final SimProcessingUnit cpu = ctx.getCpu();
             final OutPort output = stage.getOutlet("cpu");
             this.output = output;
 
@@ -416,149 +410,4 @@ public final class SimTrace {
             return Long.MAX_VALUE;
         }
     }
-
-    /**
-     * Implementation of {@link FlowStageLogic} for multiple CPUs.
-     */
-    private static class MultiWorkloadLogic implements WorkloadStageLogic {
-        private final FlowStage stage;
-        private final OutPort[] outputs;
-        private int index = 0;
-
-        private final int coreCount;
-
-        private Iterator<SimTraceFragment> fragments;
-        private SimTraceFragment currentFragment;
-        private long startOffFragment;
-
-        private final SimMachineContext ctx;
-
-        private MultiWorkloadLogic(SimMachineContext ctx, long offset, Iterator<SimTraceFragment> fragments) {
-            this.ctx = ctx;
-            this.fragments = fragments;
-
-            final FlowGraph graph = ctx.getGraph();
-            final List<? extends SimProcessingUnit> cpus = ctx.getCpus();
-
-            stage = graph.newStage(this);
-            this.coreCount = cpus.size();
-
-            final OutPort[] outputs = new OutPort[cpus.size()];
-            this.outputs = outputs;
-
-            for (int i = 0; i < cpus.size(); i++) {
-                final SimProcessingUnit cpu = cpus.get(i);
-                final OutPort output = stage.getOutlet("cpu" + i);
-
-                graph.connect(output, cpu.getInput());
-                outputs[i] = output;
-            }
-
-            this.currentFragment = this.fragments.next();
-
-            int cores = Math.min(this.coreCount, currentFragment.coreCount());
-            float usage = (float) currentFragment.cpuUsage() / cores;
-
-            // Push the usage to all active cores
-            for (int i = 0; i < cores; i++) {
-                outputs[i].push(usage);
-            }
-
-            // Push a usage of 0 to all non-active cores
-            for (int i = cores; i < outputs.length; i++) {
-                outputs[i].push(0.f);
-            }
-
-            this.startOffFragment = offset;
-        }
-
-        public long getPassedTime(long now) {
-            return now - this.startOffFragment;
-        }
-
-        @Override
-        public void updateFragments(Iterator<SimTraceFragment> newFragments, long offset) {
-            this.fragments = newFragments;
-
-            // Start the first Fragment
-            this.currentFragment = this.fragments.next();
-            int cores = Math.min(this.coreCount, currentFragment.coreCount());
-            float usage = (float) currentFragment.cpuUsage() / cores;
-
-            // Push the usage to all active cores
-            for (int i = 0; i < cores; i++) {
-                outputs[i].push(usage);
-            }
-
-            // Push a usage of 0 to all non-active cores
-            for (int i = cores; i < outputs.length; i++) {
-                outputs[i].push(0.f);
-            }
-            this.startOffFragment = offset;
-        }
-
-        @Override
-        public long onUpdate(FlowStage ctx, long now) {
-            long passedTime = now - this.startOffFragment;
-            long duration = this.currentFragment.duration();
-
-            // The current Fragment has not yet been finished, continue
-            if (passedTime < duration) {
-                return now + (duration - passedTime);
-            }
-
-            // Loop through fragments until the passed time is filled.
-            // We need a while loop to account for skipping of fragments.
-            while (passedTime >= duration) {
-
-                // Stop running
-                if (!this.fragments.hasNext()) {
-                    final SimMachineContext machineContext = this.ctx;
-                    if (machineContext != null) {
-                        machineContext.shutdown();
-                    }
-                    ctx.close();
-                    return Long.MAX_VALUE;
-                }
-
-                passedTime = passedTime - duration;
-
-                // get next Fragment
-                this.index++;
-                currentFragment = this.fragments.next();
-                duration = currentFragment.duration();
-            }
-
-            // start the new fragment
-            this.startOffFragment = now - passedTime;
-
-            int cores = Math.min(this.coreCount, currentFragment.coreCount());
-            float usage = (float) currentFragment.cpuUsage() / cores;
-
-            final OutPort[] outputs = this.outputs;
-
-            // Push the usage to all active cores
-            for (int i = 0; i < cores; i++) {
-                outputs[i].push(usage);
-            }
-
-            // Push a usage of 0 to all non-active cores
-            for (int i = cores; i < outputs.length; i++) {
-                outputs[i].push(0.f);
-            }
-
-            // Return the time when the current fragment will complete
-            return now + (duration - passedTime);
-        }
-
-        @Override
-        public FlowStage getStage() {
-            return stage;
-        }
-
-        @Override
-        public int getIndex() {
-            return index;
-        }
-    }
 }