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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: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Colin Cross 2013-05-06 23:50:10 +00:00 committed by Rafael J. Wysocki
parent 0f9548ca10
commit 18ad0c6297
1 changed files with 15 additions and 11 deletions
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26
kernel/power/process.c
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@ -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;