org.eclipse.linuxtools.lttng2.kernel.core/src/org/eclipse/linuxtools/lttng2/kernel/core/cpuusage/LttngKernelCpuStateProvider.java

   1 /*******************************************************************************
   2  * Copyright (c) 2014 École Polytechnique de Montréal
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   François Rajotte - Initial API and implementation
  11  *   Geneviève Bastien - Revision of the initial implementation
  12  *******************************************************************************/
  13
  14 package org.eclipse.linuxtools.lttng2.kernel.core.cpuusage;
  15
  16 import java.util.HashMap;
  17 import java.util.Map;
  18
  19 import org.eclipse.linuxtools.internal.lttng2.kernel.core.Activator;
  20 import org.eclipse.linuxtools.internal.lttng2.kernel.core.Attributes;
  21 import org.eclipse.linuxtools.internal.lttng2.kernel.core.LttngStrings;
  22 import org.eclipse.linuxtools.statesystem.core.exceptions.AttributeNotFoundException;
  23 import org.eclipse.linuxtools.statesystem.core.statevalue.ITmfStateValue;
  24 import org.eclipse.linuxtools.statesystem.core.statevalue.TmfStateValue;
  25 import org.eclipse.linuxtools.tmf.core.event.ITmfEvent;
  26 import org.eclipse.linuxtools.tmf.core.event.ITmfEventField;
  27 import org.eclipse.linuxtools.tmf.core.statesystem.AbstractTmfStateProvider;
  28 import org.eclipse.linuxtools.tmf.core.trace.ITmfTrace;
  29
  30 /**
  31  * Creates a state system with the total time spent on CPU for each thread and
  32  * for each CPU from a kernel trace.
  33  *
  34  * This state system in itself keeps the total time on CPU since last time the
  35  * process was scheduled out. The state system queries will only be accurate
  36  * when the process is not in a running state. To have exact CPU usage when
  37  * running, this state system needs to be used along the LTTng Kernel analysis.
  38  *
  39  * It requires only the 'sched_switch' events enabled on the trace.
  40  *
  41  * @author François Rajotte
  42  * @since 3.0
  43  */
  44 public class LttngKernelCpuStateProvider extends AbstractTmfStateProvider {
  45
  46     private static final int VERSION = 1;
  47
  48     /* For each CPU, maps the last time a thread was scheduled in */
  49     private final Map<String, Long> fLastStartTimes = new HashMap<>();
  50     private final long fTraceStart;
  51
  52     /**
  53      * Constructor
  54      *
  55      * @param trace
  56      *            The trace from which to get the CPU usage
  57      */
  58     public LttngKernelCpuStateProvider(ITmfTrace trace) {
  59         super(trace, ITmfEvent.class, "LTTng Kernel CPU usage"); //$NON-NLS-1$
  60         fTraceStart = trace.getStartTime().getValue();
  61     }
  62
  63     // ------------------------------------------------------------------------
  64     // ITmfStateProvider
  65     // ------------------------------------------------------------------------
  66
  67     @Override
  68     public int getVersion() {
  69         return VERSION;
  70     }
  71
  72     @Override
  73     public LttngKernelCpuStateProvider getNewInstance() {
  74         return new LttngKernelCpuStateProvider(this.getTrace());
  75     }
  76
  77     @Override
  78     protected void eventHandle(ITmfEvent event) {
  79         final String eventName = event.getType().getName();
  80
  81         if (eventName.equals(LttngStrings.SCHED_SWITCH)) {
  82             /*
  83              * Fields: string prev_comm, int32 prev_tid, int32 prev_prio, int64
  84              * prev_state, string next_comm, int32 next_tid, int32 next_prio
  85              */
  86
  87             ITmfEventField content = event.getContent();
  88             long ts = event.getTimestamp().getValue();
  89             String cpu = event.getSource();
  90
  91             Long prevTid = (Long) content.getField(LttngStrings.PREV_TID).getValue();
  92
  93             try {
  94                 Integer currentCPUNode = ss.getQuarkRelativeAndAdd(getNodeCPUs(), cpu);
  95
  96                 /*
  97                  * This quark contains the value of the cumulative time spent on
  98                  * the source CPU by the currently running thread
  99                  */
 100                 Integer cumulativeTimeQuark = ss.getQuarkRelativeAndAdd(currentCPUNode, prevTid.toString());
 101                 Long startTime = fLastStartTimes.get(cpu);
 102                 /*
 103                  * If start time is null, we haven't seen the start of the
 104                  * process, so we assume beginning of the trace
 105                  */
 106                 if (startTime == null) {
 107                     startTime = fTraceStart;
 108                 }
 109
 110                 /*
 111                  * We add the time from startTime until now to the cumulative
 112                  * time of the thread
 113                  */
 114                 if (startTime != null) {
 115                     ITmfStateValue value = ss.queryOngoingState(cumulativeTimeQuark);
 116
 117                     /*
 118                      * Modify cumulative time for this CPU/TID combo: The total
 119                      * time changes when the process is scheduled out. Nothing
 120                      * happens when the process is scheduled in.
 121                      */
 122                     long prevCumulativeTime = value.unboxLong();
 123                     long newCumulativeTime = prevCumulativeTime + (ts - startTime);
 124
 125                     value = TmfStateValue.newValueLong(newCumulativeTime);
 126                     ss.modifyAttribute(ts, value, cumulativeTimeQuark);
 127                     fLastStartTimes.put(cpu, ts);
 128                 }
 129             } catch (AttributeNotFoundException e) {
 130                 Activator.getDefault().logError("Attribute not found in LttngKernelCpuStateProvider", e); //$NON-NLS-1$
 131             }
 132
 133         }
 134     }
 135
 136     /* Shortcut for the "current CPU" attribute node */
 137     private int getNodeCPUs() {
 138         return ss.getQuarkAbsoluteAndAdd(Attributes.CPUS);
 139     }
 140
 141 }