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cpuset in init.rc:
# sets up initial cpusets for ActivityManager
mkdir /dev/cpuset
mount cpuset none /dev/cpuset
# this ensures that the cpusets are present and usable, but the device's
# init.rc must actually set the correct cpus
mkdir /dev/cpuset/foreground
write /dev/cpuset/foreground/cpus 0
write /dev/cpuset/foreground/mems 0
mkdir /dev/cpuset/foreground/boost
write /dev/cpuset/foreground/boost/cpus 0
write /dev/cpuset/foreground/boost/mems 0
mkdir /dev/cpuset/background
write /dev/cpuset/background/cpus 0
write /dev/cpuset/background/mems 0
# system-background is for system tasks that should only run on
# little cores, not on bigs
# to be used only by init, so don't change system-bg permissions
mkdir /dev/cpuset/system-background
write /dev/cpuset/system-background/cpus 0
write /dev/cpuset/system-background/mems 0
mkdir /dev/cpuset/top-app
write /dev/cpuset/top-app/cpus 0
write /dev/cpuset/top-app/mems 0
# change permissions for all cpusets we'll touch at runtime
chown system system /dev/cpuset
chown system system /dev/cpuset/foreground
chown system system /dev/cpuset/foreground/boost
chown system system /dev/cpuset/background
chown system system /dev/cpuset/system-background
chown system system /dev/cpuset/top-app
chown system system /dev/cpuset/tasks
chown system system /dev/cpuset/foreground/tasks
chown system system /dev/cpuset/foreground/boost/tasks
chown system system /dev/cpuset/background/tasks
chown system system /dev/cpuset/system-background/tasks
chown system system /dev/cpuset/top-app/tasks
# set system-background to 0775 so SurfaceFlinger can touch it
chmod 0775 /dev/cpuset/system-background
chmod 0664 /dev/cpuset/foreground/tasks
chmod 0664 /dev/cpuset/foreground/boost/tasks
chmod 0664 /dev/cpuset/background/tasks
chmod 0664 /dev/cpuset/system-background/tasks
chmod 0664 /dev/cpuset/top-app/tasks
chmod 0664 /dev/cpuset/tasks
# Create energy-aware scheduler tuning nodes
mkdir /dev/stune
mount cgroup none /dev/stune schedtune
mkdir /dev/stune/foreground
chown system system /dev/stune
chown system system /dev/stune/foreground
chown system system /dev/stune/tasks
chown system system /dev/stune/foreground/tasks
chmod 0664 /dev/stune/tasks
chmod 0664 /dev/stune/foreground/tasks
1. needs ENABLE_CPUSETS to be enabled in BoardConfig.mk
2. /dev/cpuset/foreground/boost: needs ENABLE_SCHED_BOOST to be enabled in BoardConfig.mk
used in files:
frameworks/base/services/core/jni/Android.mk
frameworks/base/services/core/jni/com_android_server_am_ActivityManagerService.cpp:
migrateToBoost and migrateFromBoost
static JNINativeMethod method_table[] = {
{ "nativeMigrateToBoost", "()I", (void*)migrateToBoost },
{ "nativeMigrateFromBoost", "()I", (void*)migrateFromBoost },
};
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
// app launch boost for big.little configurations
// use cpusets to migrate freshly launched tasks to big cores
nativeMigrateToBoost();
mIsBoosted = true;
mBoostStartTime = SystemClock.uptimeMillis();
Message msg = mHandler.obtainMessage(APP_BOOST_DEACTIVATE_MSG);
mHandler.sendMessageDelayed(msg, APP_BOOST_MESSAGE_DELAY);
// Delay to disable app launch boost
static final int APP_BOOST_MESSAGE_DELAY = 3000;
// Lower delay than APP_BOOST_MESSAGE_DELAY to disable the boost
static final int APP_BOOST_TIMEOUT = 2500;
case APP_BOOST_DEACTIVATE_MSG: {
synchronized(ActivityManagerService.this) {
if (mIsBoosted) {
if (mBoostStartTime < (SystemClock.uptimeMillis() - APP_BOOST_TIMEOUT)) {
nativeMigrateFromBoost();
mIsBoosted = false;
mBoostStartTime = 0;
} else {
Message newmsg = mHandler.obtainMessage(APP_BOOST_DEACTIVATE_MSG);
mHandler.sendMessageDelayed(newmsg, APP_BOOST_TIMEOUT);
}
}
}
} break;
3. /dev/stune needs ENABLE_SCHEDBOOST to be enabled in BoardConfig.mk
This is only for EAS enabled kernel.
ENABLE_SCHEDBOOST used in files:
system/core/libcutils/Android.mk
system/core/libcutils/sched_policy.c
4. /dev/cpuset/foreground, /dev/cpuset/background and /dev/cpuset/top-app
need ENABLE_CPUSETS enabled in BoardConfig.mk
ENABLE_CPUSETS used in files:
system/core/libcutils/Android.mk
system/core/libcutils/sched_policy.c
set_cpuset_policy
frameworks/native/services/surfaceflinger/main_surfaceflinger.cpp
setpriority(PRIO_PROCESS, 0, PRIORITY_URGENT_DISPLAY)
set_sched_policy(0, SP_FOREGROUND); ---> /dev/cpuctl/tasks
#ifdef ENABLE_CPUSETS
// Put most SurfaceFlinger threads in the system-background cpuset
// Keeps us from unnecessarily using big cores
// Do this after the binder thread pool init
set_cpuset_policy(0, SP_SYSTEM);
#endif
frameworks/base/core/jni/android_util_Process.cpp
android_os_Process_setProcessGroup
{"setProcessGroup", "(II)V", (void*)android_os_Process_setProcessGroup},
frameworks/base/core/java/android/os/Process.java
/**
* Sets the scheduling group for a process and all child threads
* @hide
* @param pid The identifier of the process to change.
* @param group The target group for this process from THREAD_GROUP_*.
*
* @throws IllegalArgumentException Throws IllegalArgumentException if
* <var>tid</var> does not exist.
* @throws SecurityException Throws SecurityException if your process does
* not have permission to modify the given thread, or to use the given
* priority.
*
* group == THREAD_GROUP_DEFAULT means to move all non-background priority
* threads to the foreground scheduling group, but to leave background
* priority threads alone. group == THREAD_GROUP_BG_NONINTERACTIVE moves all
* threads, regardless of priority, to the background scheduling group.
* group == THREAD_GROUP_FOREGROUND is not allowed.
*
* Always sets cpusets.
*/
public static final native void setProcessGroup(int pid, int group)
throws IllegalArgumentException, SecurityException;
frameworks/base/core/java/android/app/ActivityThread.java
public void setSchedulingGroup(int group) {
// Note: do this immediately, since going into the foreground
// should happen regardless of what pending work we have to do
// and the activity manager will wait for us to report back that
// we are done before sending us to the background.
try {
Process.setProcessGroup(Process.myPid(), group);
} catch (Exception e) {
Slog.w(TAG, "Failed setting process group to " + group, e);
}
}
13:00:54 liuyq: nougat$ grep -rn 'Process\.setProcessGroup' frameworks/
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java:20368: Process.setProcessGroup(app.pid, processGroup);
frameworks/base/core/java/android/app/ActivityThread.java:975: Process.setProcessGroup(Process.myPid(), group);
13:01:04 liuyq: nougat$
12:44:56 liuyq: nougat$ grep -rn setSchedulingGroup frameworks/
frameworks/base/core/java/android/app/IApplicationThread.java:125: void setSchedulingGroup(int group) throws RemoteException;
frameworks/base/core/java/android/app/ActivityThread.java:969: public void setSchedulingGroup(int group) {
frameworks/base/core/java/android/app/ApplicationThreadNative.java:453: setSchedulingGroup(group);
frameworks/base/core/java/android/app/ApplicationThreadNative.java:1249: public void setSchedulingGroup(int group) throws RemoteException {
12:44:59 liuyq: nougat$
Tests on hikey:
1. when write 0-7 to both /dev/cpuset/foreground/cpus and /dev/cpuset/foreground/boost/cpus, it will cause problem to write task id to /dev/cpuset/foreground/cpus, seens cpuset and it's subset could not use the same set of cpus. but the root cpuset is an exception.
It will report "Device or Resource is busy"
2. could not write multiple lines into the cpus files, like the return line
it will report Argument list is too long error
3. When there is no cpus file for one cpuset, write to tasks operation will fail,
and report "No space" problem
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