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Commit c8a02c5a authored by Edgar Arriaga's avatar Edgar Arriaga
Browse files

Add threshold to downgrade compaction when swap is low 

This patch introduces a threshold that allows compaction
system to downgrade full compactions into file only compactions
which do not cause compactions to happen as a way to reduce
pressure on swap thus aiming for a reduction in overall cpu
usage during high memory pressure scenarios as finding new
pages will likely be harder when the swap is low.

Bug: 226458732
Test: Manual. Verified that compaction runs artificially using different
thresholds and logging.

Change-Id: I12b460174c857f6750c9a173997c66381e4a1dc3
parent 834aee5d

services/core/java/com/android/server/am/CachedAppOptimizer.java

+22 −0
Original line number Diff line number Diff line
@@ -152,6 +152,11 @@ public final class CachedAppOptimizer { 
    static final int SET_FROZEN_PROCESS_MSG = 3;

    static final int REPORT_UNFREEZE_MSG = 4;



    // When free swap falls below this percentage threshold any full (file + anon)

    // compactions will be downgraded to file only compactions to reduce pressure

    // on swap resources as file.

    static final double COMPACT_DOWNGRADE_FREE_SWAP_THRESHOLD = 0.2;



    static final int DO_FREEZE = 1;

    static final int REPORT_UNFREEZE = 2;
@@ -544,6 +549,11 @@ public final class CachedAppOptimizer { 


    static private native void cancelCompaction();



    /**

     * Retrieves the free swap percentage.

     */

    static private native double getFreeSwapPercent();



    /**

     * Reads the flag value from DeviceConfig to determine whether app compaction

     * should be enabled, and starts the freeze/compaction thread if needed.
@@ -1338,6 +1348,18 @@ public final class CachedAppOptimizer { 
                        default:

                            break;

                    }

                    // Downgrade compaction if facing swap memory pressure

                    if (action.equals(mCompactActionFull)) {

                        double swapUsagePercent = getFreeSwapPercent();

                        if (swapUsagePercent < COMPACT_DOWNGRADE_FREE_SWAP_THRESHOLD) {

                            Slog.d(TAG_AM,

                                    "Downgraded compaction to file only due to low swap."

                                            + " Swap Free% " + swapUsagePercent);

                            action = mCompactActionSome;

                            pendingAction = COMPACT_PROCESS_SOME;

                        }

                    }



                    try {

                        Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "Compact "

                                + ((pendingAction == COMPACT_PROCESS_SOME) ? "some" : "full")

services/core/jni/com_android_server_am_CachedAppOptimizer.cpp

+13 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <sys/pidfd.h>

#include <sys/stat.h>

#include <sys/syscall.h>

#include <sys/sysinfo.h>

#include <sys/types.h>

#include <unistd.h>
@@ -305,6 +306,16 @@ static void com_android_server_am_CachedAppOptimizer_cancelCompaction(JNIEnv*, j 
    }

}



static jdouble com_android_server_am_CachedAppOptimizer_getFreeSwapPercent(JNIEnv*, jobject) {

    struct sysinfo memoryInfo;

    int error = sysinfo(&memoryInfo);

    if(error == -1) {

        LOG(ERROR) << "Could not check free swap space";

        return 0;

    }

    return (double)memoryInfo.freeswap / (double)memoryInfo.totalswap;

}



static void com_android_server_am_CachedAppOptimizer_compactProcess(JNIEnv*, jobject, jint pid,

                                                                    jint compactionFlags) {

    compactProcessOrFallback(pid, compactionFlags);
@@ -358,6 +369,8 @@ static const JNINativeMethod sMethods[] = { 
        /* name, signature, funcPtr */

        {"cancelCompaction", "()V",

         (void*)com_android_server_am_CachedAppOptimizer_cancelCompaction},

        {"getFreeSwapPercent", "()D",

         (void*)com_android_server_am_CachedAppOptimizer_getFreeSwapPercent},

        {"compactSystem", "()V", (void*)com_android_server_am_CachedAppOptimizer_compactSystem},

        {"compactProcess", "(II)V", (void*)com_android_server_am_CachedAppOptimizer_compactProcess},

        {"freezeBinder", "(IZ)I", (void*)com_android_server_am_CachedAppOptimizer_freezeBinder},