On 11/09/2011 08:40 PM, Andrea Arcangeli wrote:
> On Wed, Nov 09, 2011 at 10:34:47AM -0800, Tejun Heo wrote:
>> know. My instinct tells me to strongly recommend use of
>> wait_event_freezable_timeout() and run away. :)
>
> Passing false wasn't so appealing to me but ok. Jiri can you test this
> with some suspend? (beware builds but untested)
>
> ===
> From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Subject: thp: reduce khugepaged freezing latency
>
> 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@xxxxxxx>
Tested-by: Jiri Slaby <jslaby@xxxxxxx>
> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 14 ++++----------
> 1 files changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4298aba..fd925d0 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2259,12 +2259,9 @@ 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 +2310,11 @@ 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(
> + wait_event_freezable_timeout(khugepaged_wait, false,
> msecs_to_jiffies(
> khugepaged_scan_sleep_millisecs));
> - remove_wait_queue(&khugepaged_wait, &wait);
> } else if (khugepaged_enabled())
> wait_event_freezable(khugepaged_wait,
> khugepaged_wait_event());
thanks,
--
js
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