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PM / freezer: Don't get over-anxious while waiting 

Freezing isn't exactly the most latency sensitive operation and
there's no reason to burn cpu cycles and power waiting for it to
complete.  msleep(10) instead of yield().  This should improve
reliability of emergency hibernation.

[rjw: Modified the comment next to the msleep(10).]

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
Tejun Heo 2009-10-08 22:47:30 +02:00 committed by Rafael J. Wysocki
parent 964fe080d9
commit be404f0212
1 changed files with 10 additions and 4 deletions
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14
kernel/power/process.c
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@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
#include <linux/delay.h>
/*
* Timeout for stopping processes
@ -41,7 +42,7 @@ static int try_to_freeze_tasks(bool sig_only)
do_gettimeofday(&start);
end_time = jiffies + TIMEOUT;
do {
while (true) {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
@ -62,10 +63,15 @@ static int try_to_freeze_tasks(bool sig_only)
todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
if (time_after(jiffies, end_time))
if (!todo || time_after(jiffies, end_time))
break;
} while (todo);
/*
* We need to retry, but first give the freezing tasks some
* time to enter the regrigerator.
*/
msleep(10);
}
do_gettimeofday(&end);
elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);