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Commit 29a3a5b1 authored by Edgar Arriaga's avatar Edgar Arriaga
Browse files

Cancel compaction if the process improves its OOM ranking while compaction is running 

There is a significant delay between the time we issue a compaction and when its done
during this time the OOM adjust sometimes changes, however, the current compaction
still keeps running, which leads to situations where proc A starts running
while compaction for proc A is happening leading to long delays as compaction
grabs the mmap_lock thus not allowing for allocations to happen during that time

So the aim of this CL is to reduce the likelihood of such situations by avoiding
continuing compaction when we detect such OOM adjust improvement outside of cache state.
Note that we do not kill the currently running process_madvise, instead we avoid
issuing new process_madvise calls so this will likely improve situations where an app has
many VMAs.

Test: Manual. Checked that JNI callback happens and that OOM adjusts match
as well as checked that compaction is cancelled when the improvement in OOM happens.

Bug: 208966958
Change-Id: I202a96d884e2a0dc7ac7013eca91a36cd58acc80
parent ab30d8d8

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

+33 −0
Original line number Diff line number Diff line
@@ -539,6 +539,8 @@ public final class CachedAppOptimizer { 
     */

    static private native void compactProcess(int pid, int compactionFlags);



    static private native void cancelCompaction();



    /**

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

     * should be enabled, and starts the freeze/compaction thread if needed.
@@ -1049,6 +1051,26 @@ public final class CachedAppOptimizer { 
        }

    }



    @GuardedBy({"mService", "mProcLock"})

    void onOomAdjustChanged(int oldAdj, int newAdj, ProcessRecord app) {

        // Cancel any currently executing compactions

        // if the process moved out of cached state

        if (DefaultProcessDependencies.mPidCompacting == app.mPid && newAdj < oldAdj

                && newAdj < ProcessList.CACHED_APP_MIN_ADJ) {

            cancelCompaction();

        }



        // Perform a minor compaction when a perceptible app becomes the prev/home app

        // Perform a major compaction when any app enters cached

        if (oldAdj <= ProcessList.PERCEPTIBLE_APP_ADJ

                && (newAdj == ProcessList.PREVIOUS_APP_ADJ || newAdj == ProcessList.HOME_APP_ADJ)) {

            compactAppSome(app);

        } else if (newAdj >= ProcessList.CACHED_APP_MIN_ADJ

                && newAdj <= ProcessList.CACHED_APP_MAX_ADJ) {

            compactAppFull(app);

        }

    }



    @VisibleForTesting

    static final class LastCompactionStats {

        private final long[] mRssAfterCompaction;
@@ -1091,6 +1113,13 @@ public final class CachedAppOptimizer { 
                        name = proc.processName;

                        opt.setHasPendingCompact(false);



                        if (mAm.mInternal.isPendingTopUid(proc.uid)) {

                            // In case the OOM Adjust has not yet been propagated we see if this is

                            // pending on becoming top app in which case we should not compact.

                            Slog.e(TAG_AM, "Skip compaction since UID is active for  " + name);

                            return;

                        }



                        // don't compact if the process has returned to perceptible

                        // and this is only a cached/home/prev compaction

                        if ((pendingAction == COMPACT_PROCESS_SOME
@@ -1500,6 +1529,8 @@ public final class CachedAppOptimizer { 
     * Default implementation for ProcessDependencies, public vor visibility to OomAdjuster class.

     */

    private static final class DefaultProcessDependencies implements ProcessDependencies {

        public static int mPidCompacting = -1;



        // Get memory RSS from process.

        @Override

        public long[] getRss(int pid) {
@@ -1509,6 +1540,7 @@ public final class CachedAppOptimizer { 
        // Compact process.

        @Override

        public void performCompaction(String action, int pid) throws IOException {

            mPidCompacting = pid;

            if (action.equals(COMPACT_ACTION_STRING[COMPACT_ACTION_FULL])) {

                compactProcess(pid, COMPACT_ACTION_FILE_FLAG | COMPACT_ACTION_ANON_FLAG);

            } else if (action.equals(COMPACT_ACTION_STRING[COMPACT_ACTION_FILE])) {
@@ -1516,6 +1548,7 @@ public final class CachedAppOptimizer { 
            } else if (action.equals(COMPACT_ACTION_STRING[COMPACT_ACTION_ANON])) {

                compactProcess(pid, COMPACT_ACTION_ANON_FLAG);

            }

            mPidCompacting = -1;

        }

    }

}

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

+2 −11
Original line number Diff line number Diff line
@@ -2486,18 +2486,9 @@ public class OomAdjuster { 
        // don't compact during bootup

        if (mCachedAppOptimizer.useCompaction() && mService.mBooted) {

            // Cached and prev/home compaction

            if (state.getCurAdj() != state.getSetAdj()) {

                // Perform a minor compaction when a perceptible app becomes the prev/home app

                // Perform a major compaction when any app enters cached

            // reminder: here, setAdj is previous state, curAdj is upcoming state

                if (state.getSetAdj() <= ProcessList.PERCEPTIBLE_APP_ADJ

                        && (state.getCurAdj() == ProcessList.PREVIOUS_APP_ADJ

                            || state.getCurAdj() == ProcessList.HOME_APP_ADJ)) {

                    mCachedAppOptimizer.compactAppSome(app);

                } else if (state.getCurAdj() >= ProcessList.CACHED_APP_MIN_ADJ

                        && state.getCurAdj() <= ProcessList.CACHED_APP_MAX_ADJ) {

                    mCachedAppOptimizer.compactAppFull(app);

                }

            if (state.getCurAdj() != state.getSetAdj()) {

                mCachedAppOptimizer.onOomAdjustChanged(state.getSetAdj(), state.getCurAdj(), app);

            } else if (mService.mWakefulness.get() != PowerManagerInternal.WAKEFULNESS_AWAKE

                    && state.getSetAdj() < ProcessList.FOREGROUND_APP_ADJ

                    // Because these can fire independent of oom_adj/procstate changes, we need

services/core/jni/com_android_server_am_CachedAppOptimizer.cpp

+22 −0
Original line number Diff line number Diff line
@@ -59,6 +59,9 @@ using android::base::unique_fd; 


namespace android {



static bool cancelRunningCompaction;

static bool compactionInProgress;



// Legacy method for compacting processes, any new code should

// use compactProcess instead.

static inline void compactProcessProcfs(int pid, const std::string& compactionType) {
@@ -83,9 +86,18 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT 
        // Skip compaction if failed to open pidfd with any error

        return -errno;

    }

    compactionInProgress = true;

    cancelRunningCompaction = false;



    int64_t totalBytesCompacted = 0;

    for (int iBase = 0; iBase < vmas.size(); iBase += UIO_MAXIOV) {

        if (CC_UNLIKELY(cancelRunningCompaction)) {

            // There could be a significant delay betweenwhen a compaction

            // is requested and when it is handled during this time

            // our OOM adjust could have improved.

            cancelRunningCompaction = false;

            break;

        }

        int totalVmasToKernel = std::min(UIO_MAXIOV, (int)(vmas.size() - iBase));

        for (int iVec = 0, iVma = iBase; iVec < totalVmasToKernel; ++iVec, ++iVma) {

            vmasToKernel[iVec].iov_base = (void*)vmas[iVma].start;
@@ -95,11 +107,13 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT 
        auto bytesCompacted =

                process_madvise(pidfd, vmasToKernel, totalVmasToKernel, madviseType, 0);

        if (CC_UNLIKELY(bytesCompacted == -1)) {

            compactionInProgress = false;

            return -errno;

        }



        totalBytesCompacted += bytesCompacted;

    }

    compactionInProgress = false;



    return totalBytesCompacted;

}
@@ -228,6 +242,12 @@ static void com_android_server_am_CachedAppOptimizer_compactSystem(JNIEnv *, job 
    }

}



static void com_android_server_am_CachedAppOptimizer_cancelCompaction(JNIEnv*, jobject) {

    if (compactionInProgress) {

        cancelRunningCompaction = true;

    }

}



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

                                                                    jint compactionFlags) {

    compactProcessOrFallback(pid, compactionFlags);
@@ -279,6 +299,8 @@ static jstring com_android_server_am_CachedAppOptimizer_getFreezerCheckPath(JNIE 


static const JNINativeMethod sMethods[] = {

        /* name, signature, funcPtr */

        {"cancelCompaction", "()V",

         (void*)com_android_server_am_CachedAppOptimizer_cancelCompaction},

        {"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},