am 253e27ac: Optimize set_sched_policy(), which gets called in every binder call. (ba9025ce) · Commits · e / os / android_system_core

libcutils/sched_policy.c

+22 −16

Original line number	Diff line number	Diff line
		@@ -44,22 +44,27 @@

		static int __sys_supports_schedgroups = -1;

		static int add_tid_to_cgroup(int tid, const char *grp_name)
		/* Add tid to the group defined by dev_path ("/dev/cpuctl/.../tasks") */
		static int add_tid_to_cgroup(int tid, const char *dev_path)
		{
		int fd;
		char path[255];
		char text[64];

		sprintf(path, "/dev/cpuctl/%s/tasks", grp_name);

		if ((fd = open(path, O_WRONLY)) < 0) {
		SLOGE("add_tid_to_cgroup failed to open '%s' (%s)\n", path,
		if ((fd = open(dev_path, O_WRONLY)) < 0) {
		SLOGE("add_tid_to_cgroup failed to open '%s' (%s)\n", dev_path,
		strerror(errno));
		return -1;
		}

		sprintf(text, "%d", tid);
		if (write(fd, text, strlen(text)) < 0) {
		// specialized itoa -- works for tid > 0
		char text[22];
		char *end = text + sizeof(text) - 1;
		char *ptr = end;
		*ptr = '\0';
		while (tid > 0) {
		*--ptr = '0' + (tid % 10);
		tid = tid / 10;
		}

		if (write(fd, ptr, end - ptr) < 0) {
		close(fd);
		/*
		* If the thread is in the process of exiting,
		@@ -67,8 +72,8 @@ static int add_tid_to_cgroup(int tid, const char *grp_name)
		*/
		if (errno == ESRCH)
		return 0;
		SLOGW("add_tid_to_cgroup failed to write '%s' (%s)\n", path,
		strerror(errno));
		SLOGW("add_tid_to_cgroup failed to write '%s' to '%s' (%s)\n",
		ptr, dev_path, strerror(errno));
		return -1;
		}

		@@ -228,13 +233,14 @@ int set_sched_policy(int tid, SchedPolicy policy)
		#endif

		if (__sys_supports_schedgroups) {
		const char *grp = "";

		const char *dev_path;
		if (policy == SP_BACKGROUND) {
		grp = "bg_non_interactive";
		dev_path = "/dev/cpuctl/bg_non_interactive/tasks";
		} else {
		dev_path = "/dev/cpuctl/tasks";
		}

		if (add_tid_to_cgroup(tid, grp)) {
		if (add_tid_to_cgroup(tid, dev_path)) {
		if (errno != ESRCH && errno != ENOENT)
		return -errno;
		}