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Commit 181ff707 authored by T.J. Mercier's avatar T.J. Mercier
Browse files

Remove fallback to /proc/pid/reclaim during app compaction 

The /proc/pid/reclaim interface existed only on some device kernels, and
only until 4.19 which is now end of life (Dec. 2024). This UAPI was never upstream.

Bug: 374811051
Flag: EXEMPT cleanup
Change-Id: Ic7058c57d9ed25c3a100431dc5f9946dfa5b14ee
parent 74fac640

services/core/jni/com_android_server_am_CachedAppOptimizer.cpp

+5 −23
Original line number Diff line number Diff line
@@ -263,13 +263,6 @@ int madviseVmasFromBatch(unique_fd& pidfd, VmaBatch& batch, int madviseType, 
    return 0;

}



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

// use compactProcess instead.

static inline void compactProcessProcfs(int pid, const std::string& compactionType) {

    std::string reclaim_path = StringPrintf("/proc/%d/reclaim", pid);

    WriteStringToFile(compactionType, reclaim_path);

}



// Compacts a set of VMAs for pid using an madviseType accepted by process_madvise syscall

// Returns the total bytes that where madvised.

//
@@ -413,37 +406,26 @@ static int64_t compactProcess(int pid, VmaToAdviseFunc vmaToAdviseFunc) { 
    return pageoutBytes + coldBytes;

}



// Compact process using process_madvise syscall or fallback to procfs in

// case syscall does not exist.

static void compactProcessOrFallback(int pid, int compactionFlags) {

// Compact process using process_madvise syscall

static void compactProcess(int pid, int compactionFlags) {

    if ((compactionFlags & (COMPACT_ACTION_ANON_FLAG | COMPACT_ACTION_FILE_FLAG)) == 0) return;



    bool compactAnon = compactionFlags & COMPACT_ACTION_ANON_FLAG;

    bool compactFile = compactionFlags & COMPACT_ACTION_FILE_FLAG;



    // Set when the system does not support process_madvise syscall to avoid

    // gathering VMAs in subsequent calls prior to falling back to procfs

    static bool shouldForceProcFs = false;

    std::string compactionType;

    VmaToAdviseFunc vmaToAdviseFunc;



    if (compactAnon) {

        if (compactFile) {

            compactionType = "all";

            vmaToAdviseFunc = getAnyPageAdvice;

        } else {

            compactionType = "anon";

            vmaToAdviseFunc = getAnonPageAdvice;

        }

    } else {

        compactionType = "file";

        vmaToAdviseFunc = getFilePageAdvice;

    }



    if (shouldForceProcFs || compactProcess(pid, vmaToAdviseFunc) == -ENOSYS) {

        shouldForceProcFs = true;

        compactProcessProcfs(pid, compactionType);

    }

    compactProcess(pid, vmaToAdviseFunc);

}



// This performs per-process reclaim on all processes belonging to non-app UIDs.
@@ -481,7 +463,7 @@ static void com_android_server_am_CachedAppOptimizer_compactSystem(JNIEnv *, job 


        int pid = atoi(current->d_name);



        compactProcessOrFallback(pid, COMPACT_ACTION_ANON_FLAG | COMPACT_ACTION_FILE_FLAG);

        compactProcess(pid, COMPACT_ACTION_ANON_FLAG | COMPACT_ACTION_FILE_FLAG);

    }

}
@@ -518,7 +500,7 @@ static jlong com_android_server_am_CachedAppOptimizer_getMemoryFreedCompaction() 


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

                                                                    jint compactionFlags) {

    compactProcessOrFallback(pid, compactionFlags);

    compactProcess(pid, compactionFlags);

}



static const JNINativeMethod sMethods[] = {