From: Mel Gorman <mel@csn.ul.ie>
To: Christoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel List <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails
Date: Thu, 9 Sep 2010 14:55:23 +0100 [thread overview]
Message-ID: <20100909135523.GA340@csn.ul.ie> (raw)
In-Reply-To: <alpine.DEB.2.00.1009090843480.18975@router.home>
On Thu, Sep 09, 2010 at 08:45:16AM -0500, Christoph Lameter wrote:
> On Thu, 9 Sep 2010, Mel Gorman wrote:
>
> > @@ -1876,10 +1890,13 @@ retry:
> > migratetype);
> >
> > /*
> > - * If an allocation failed after direct reclaim, it could be because
> > - * pages are pinned on the per-cpu lists. Drain them and try again
> > + * If a high-order allocation failed after direct reclaim, it could
> > + * be because pages are pinned on the per-cpu lists. However, only
> > + * do it for PAGE_ALLOC_COSTLY_ORDER as the cost of the IPI needed
> > + * to drain the pages is itself high. Assume that lower orders
> > + * will naturally free without draining.
> > */
> > - if (!page && !drained) {
> > + if (!page && !drained && order > PAGE_ALLOC_COSTLY_ORDER) {
> > drain_all_pages();
> > drained = true;
> > goto retry;
> >
>
> This will have the effect of never sending IPIs for slab allocations since
> they do not do allocations for orders > PAGE_ALLOC_COSTLY_ORDER.
>
The question is how severe is that? There is somewhat of an expectation
that the lower orders free naturally so it the IPI justified? That said,
our historical behaviour would have looked like
if (!page && !drained && order) {
drain_all_pages();
draiained = true;
goto retry;
}
Play it safe for now and go with that?
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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next prev parent reply other threads:[~2010-09-09 13:55 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-03 9:08 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V4 Mel Gorman
2010-09-03 9:08 ` [PATCH 1/3] mm: page allocator: Update free page counters after pages are placed on the free list Mel Gorman
2010-09-03 22:38 ` Andrew Morton
2010-09-05 18:06 ` Mel Gorman
2010-09-03 9:08 ` [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake Mel Gorman
2010-09-03 22:55 ` Andrew Morton
2010-09-03 23:17 ` Christoph Lameter
2010-09-03 23:28 ` Andrew Morton
2010-09-04 0:54 ` Christoph Lameter
2010-09-05 18:12 ` Mel Gorman
2010-09-03 9:08 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-09-03 23:00 ` Andrew Morton
2010-09-04 2:25 ` Dave Chinner
2010-09-04 3:21 ` Andrew Morton
2010-09-04 7:58 ` Dave Chinner
2010-09-04 8:14 ` Dave Chinner
[not found] ` <20100905015400.GA10714@localhost>
[not found] ` <20100905021555.GG705@dastard>
[not found] ` <20100905060539.GA17450@localhost>
[not found] ` <20100905131447.GJ705@dastard>
2010-09-05 13:45 ` Wu Fengguang
2010-09-05 23:33 ` Dave Chinner
2010-09-06 4:02 ` Dave Chinner
2010-09-06 8:40 ` Mel Gorman
2010-09-06 21:50 ` Dave Chinner
2010-09-08 8:49 ` Dave Chinner
2010-09-09 12:39 ` Mel Gorman
2010-09-10 6:17 ` Dave Chinner
2010-09-07 14:23 ` Christoph Lameter
2010-09-08 2:13 ` Wu Fengguang
2010-09-04 3:23 ` Wu Fengguang
2010-09-04 3:59 ` Andrew Morton
2010-09-04 4:37 ` Wu Fengguang
2010-09-05 18:22 ` Mel Gorman
2010-09-05 18:14 ` Mel Gorman
2010-09-08 7:43 ` KOSAKI Motohiro
2010-09-08 20:05 ` Christoph Lameter
2010-09-09 12:41 ` Mel Gorman
2010-09-09 13:45 ` Christoph Lameter
2010-09-09 13:55 ` Mel Gorman [this message]
2010-09-09 14:32 ` Christoph Lameter
2010-09-09 15:05 ` Mel Gorman
2010-09-10 2:56 ` KOSAKI Motohiro
2010-09-03 23:05 ` [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V4 Andrew Morton
2010-09-21 11:17 ` Mel Gorman
2010-09-21 12:58 ` [stable] " Greg KH
2010-09-21 14:23 ` Mel Gorman
2010-09-23 18:49 ` Greg KH
2010-09-24 9:14 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2010-08-31 17:37 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V3 Mel Gorman
2010-08-31 17:37 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-08-31 18:26 ` Christoph Lameter
2010-08-23 8:00 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V2 Mel Gorman
2010-08-23 8:00 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-08-23 23:17 ` KOSAKI Motohiro
2010-08-16 9:42 [RFC PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator Mel Gorman
2010-08-16 9:42 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-08-16 14:50 ` Rik van Riel
2010-08-17 2:57 ` Minchan Kim
2010-08-18 3:02 ` KAMEZAWA Hiroyuki
2010-08-19 14:47 ` Minchan Kim
2010-08-19 15:10 ` Mel Gorman
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