PM / freezer: Don't get over-anxious while waiting (be404f02) · Commits · 戴 / test

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>

kernel/power/process.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -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);

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