Commit 1dfb059b authored Dec 08, 2011 by Andrea Arcangeli Committed by Linus Torvalds Dec 09, 2011

thp: reduce khugepaged freezing latency



khugepaged can sometimes cause suspend to fail, requiring that the user
retry the suspend operation.

Use wait_event_freezable_timeout() instead of
schedule_timeout_interruptible() to avoid missing freezer wakeups.  A
try_to_freeze() would have been needed in the khugepaged_alloc_hugepage
tight loop too in case of the allocation failing repeatedly, and
wait_event_freezable_timeout will provide it too.

khugepaged would still freeze just fine by trying again the next minute
but it's better if it freezes immediately.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent b53fc7c2

mm/huge_memory.c

+4 −12

Original line number	Diff line number	Diff line
		@@ -2259,12 +2259,8 @@ static void khugepaged_do_scan(struct page **hpage)

		static void khugepaged_alloc_sleep(void)
		{
		DEFINE_WAIT(wait);
		add_wait_queue(&khugepaged_wait, &wait);
		schedule_timeout_interruptible(
		msecs_to_jiffies(
		khugepaged_alloc_sleep_millisecs));
		remove_wait_queue(&khugepaged_wait, &wait);
		wait_event_freezable_timeout(khugepaged_wait, false,
		msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
		}

		#ifndef CONFIG_NUMA
		@@ -2313,14 +2309,10 @@ static void khugepaged_loop(void)
		if (unlikely(kthread_should_stop()))
		break;
		if (khugepaged_has_work()) {
		DEFINE_WAIT(wait);
		if (!khugepaged_scan_sleep_millisecs)
		continue;
		add_wait_queue(&khugepaged_wait, &wait);
		schedule_timeout_interruptible(
		msecs_to_jiffies(
		khugepaged_scan_sleep_millisecs));
		remove_wait_queue(&khugepaged_wait, &wait);
		wait_event_freezable_timeout(khugepaged_wait, false,
		msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
		} else if (khugepaged_enabled())
		wait_event_freezable(khugepaged_wait,
		khugepaged_wait_event());

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