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Commit 01fad4a5 authored by Brad Fitzpatrick's avatar Brad Fitzpatrick
Browse files

Ease contention on the mProcessStatsThread mutex in updateCpuStats. 

BUG=2606839

Change-Id: I444af0bb4a7b0be7ebf9ee5887805f2f09a426d0
parent 975d86df

services/java/com/android/server/am/ActivityManagerService.java

+17 −9
Original line number Diff line number Diff line
@@ -123,6 +123,8 @@ import java.util.List; 
import java.util.Locale;

import java.util.Map;

import java.util.Set;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.atomic.AtomicLong;















public final class ActivityManagerService extends ActivityManagerNative implements Watchdog.Monitor {















    static final String TAG = "ActivityManager";










@@ -927,7 +929,9 @@ public final class ActivityManagerService extends ActivityManagerNative implemen













     */















    final ProcessStats mProcessStats = new ProcessStats(















            MONITOR_THREAD_CPU_USAGE);













    long mLastCpuTime = 0;













    final AtomicLong mLastCpuTime = new AtomicLong(0);













    final AtomicBoolean mProcessStatsMutexFree = new AtomicBoolean(true);



























    long mLastWriteTime = 0;





























    long mInitialStartTime = 0;










@@ -1430,7 +1434,7 @@ public final class ActivityManagerService extends ActivityManagerNative implemen













                        try {















                            synchronized(this) {















                                final long now = SystemClock.uptimeMillis();













                                long nextCpuDelay = (mLastCpuTime+MONITOR_CPU_MAX_TIME)-now;













                                long nextCpuDelay = (mLastCpuTime.get()+MONITOR_CPU_MAX_TIME)-now;















                                long nextWriteDelay = (mLastWriteTime+BATTERY_STATS_TIME)-now;















                                //Slog.i(TAG, "Cpu delay=" + nextCpuDelay















                                //        + ", write delay=" + nextWriteDelay);









@@ -1438,12 +1442,12 @@ public final class ActivityManagerService extends ActivityManagerNative implemen













                                    nextCpuDelay = nextWriteDelay;















                                }















                                if (nextCpuDelay > 0) {













                                    mProcessStatsMutexFree.set(true);















                                    this.wait(nextCpuDelay);















                                }















                            }















                        } catch (InterruptedException e) {















                        }













                        















                        updateCpuStatsNow();















                    } catch (Exception e) {















                        Slog.e(TAG, "Unexpected exception collecting process stats", e);









@@ -1470,9 +1474,12 @@ public final class ActivityManagerService extends ActivityManagerNative implemen













    }





























    void updateCpuStats() {













        synchronized (mProcessStatsThread) {















        final long now = SystemClock.uptimeMillis();













            if (mLastCpuTime < (now-MONITOR_CPU_MIN_TIME)) {













        if (mLastCpuTime.get() >= now - MONITOR_CPU_MIN_TIME) {













            return;













        }













        if (mProcessStatsMutexFree.compareAndSet(true, false)) {













            synchronized (mProcessStatsThread) {















                mProcessStatsThread.notify();















            }















        }









@@ -1480,12 +1487,13 @@ public final class ActivityManagerService extends ActivityManagerNative implemen



























    void updateCpuStatsNow() {















        synchronized (mProcessStatsThread) {













            mProcessStatsMutexFree.set(false);















            final long now = SystemClock.uptimeMillis();















            boolean haveNewCpuStats = false;





























            if (MONITOR_CPU_USAGE &&













                    mLastCpuTime < (now-MONITOR_CPU_MIN_TIME)) {













                mLastCpuTime = now;













                    mLastCpuTime.get() < (now-MONITOR_CPU_MIN_TIME)) {













                mLastCpuTime.set(now);















                haveNewCpuStats = true;















                mProcessStats.update();















                //Slog.i(TAG, mProcessStats.printCurrentState());