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Commit 6d43a861 authored by Tim Murray's avatar Tim Murray
Browse files

Add boost to increase the load on newly-forked zygote processes. 

Makes it more likely for app launches to end up on a large core in
an HMP environment.

bug 21915482

Change-Id: Ieac192a4bc1237dd03b9492fcad3a78de5510a58
parent e229337b

core/jni/Android.mk

+4 −0
Original line number Diff line number Diff line
@@ -20,6 +20,10 @@ ifneq ($(ENABLE_CPUSETS),) 
    LOCAL_CFLAGS += -DENABLE_CPUSETS

endif



ifneq ($(ENABLE_SCHED_BOOST),)

    LOCAL_CFLAGS += -DENABLE_SCHED_BOOST

endif



LOCAL_CFLAGS += -DGL_GLEXT_PROTOTYPES -DEGL_EGLEXT_PROTOTYPES



LOCAL_CFLAGS += -DU_USING_ICU_NAMESPACE=0

core/jni/com_android_internal_os_Zygote.cpp

+31 −0
Original line number Diff line number Diff line
@@ -408,6 +408,27 @@ void SetThreadName(const char* thread_name) { 
  }

}



#ifdef ENABLE_SCHED_BOOST

static void SetForkLoad(bool boost) {

  // set scheduler knob to boost forked processes

  pid_t currentPid = getpid();

  // fits at most "/proc/XXXXXXX/sched_init_task_load\0"

  char schedPath[35];

  snprintf(schedPath, sizeof(schedPath), "/proc/%u/sched_init_task_load", currentPid);

  int schedBoostFile = open(schedPath, O_WRONLY);

  if (schedBoostFile < 0) {

    ALOGW("Unable to set zygote scheduler boost");

    return;

  }

  if (boost) {

    write(schedBoostFile, "100\0", 4);

  } else {

    write(schedBoostFile, "0\0", 2);

  }

  close(schedBoostFile);

}

#endif



// Utility routine to fork zygote and specialize the child process.

static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,

                                     jint debug_flags, jobjectArray javaRlimits,
@@ -418,6 +439,10 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra 
                                     jstring instructionSet, jstring dataDir) {

  SetSigChldHandler();



#ifdef ENABLE_SCHED_BOOST

  SetForkLoad(true);

#endif



  pid_t pid = fork();



  if (pid == 0) {
@@ -558,6 +583,12 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra 
    }

  } else if (pid > 0) {

    // the parent process



#ifdef ENABLE_SCHED_BOOST

    // unset scheduler knob

    SetForkLoad(false);

#endif



  }

  return pid;

}