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Commit 18ad0c62 authored by Colin Cross's avatar Colin Cross Committed by Rafael J. Wysocki
Browse files

freezer: shorten freezer sleep time using exponential backoff 



All tasks can easily be frozen in under 10 ms, switch to using
an initial 1 ms sleep followed by exponential backoff until
8 ms.  Also convert the printed time to ms instead of centiseconds.

Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarColin Cross <ccross@android.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 0f9548ca

kernel/power/process.c

+15 −11
Original line number Diff line number Diff line
@@ -30,9 +30,10 @@ static int try_to_freeze_tasks(bool user_only) 
	unsigned int todo;

	bool wq_busy = false;

	struct timeval start, end;

	u64 elapsed_csecs64;

	unsigned int elapsed_csecs;

	u64 elapsed_msecs64;

	unsigned int elapsed_msecs;

	bool wakeup = false;

	int sleep_usecs = USEC_PER_MSEC;



	do_gettimeofday(&start);
@@ -68,22 +69,25 @@ static int try_to_freeze_tasks(bool user_only) 


		/*

		 * We need to retry, but first give the freezing tasks some

		 * time to enter the refrigerator.

		 * time to enter the refrigerator.  Start with an initial

		 * 1 ms sleep followed by exponential backoff until 8 ms.

		 */

		msleep(10);

		usleep_range(sleep_usecs / 2, sleep_usecs);

		if (sleep_usecs < 8 * USEC_PER_MSEC)

			sleep_usecs *= 2;

	}



	do_gettimeofday(&end);

	elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);

	do_div(elapsed_csecs64, NSEC_PER_SEC / 100);

	elapsed_csecs = elapsed_csecs64;

	elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);

	do_div(elapsed_msecs64, NSEC_PER_MSEC);

	elapsed_msecs = elapsed_msecs64;



	if (todo) {

		printk("\n");

		printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "

		printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "

		       "(%d tasks refusing to freeze, wq_busy=%d):\n",

		       wakeup ? "aborted" : "failed",

		       elapsed_csecs / 100, elapsed_csecs % 100,

		       elapsed_msecs / 1000, elapsed_msecs % 1000,

		       todo - wq_busy, wq_busy);



		if (!wakeup) {
@@ -96,8 +100,8 @@ static int try_to_freeze_tasks(bool user_only) 
			read_unlock(&tasklist_lock);

		}

	} else {

		printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,

			elapsed_csecs % 100);

		printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,

			elapsed_msecs % 1000);

	}



	return todo ? -EBUSY : 0;