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 16:05:58 +0100 [thread overview]
Message-ID: <20100909150558.GB340@csn.ul.ie> (raw)
In-Reply-To: <alpine.DEB.2.00.1009090931360.18975@router.home>
On Thu, Sep 09, 2010 at 09:32:52AM -0500, Christoph Lameter wrote:
> On Thu, 9 Sep 2010, Mel Gorman wrote:
>
> > > 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?
>
> I am fine with no IPIs for order <= COSTLY. Just be aware that this is
> a change that may have some side effects.
I made the choice consciously. I felt that if slab or slub were depending on
IPIs to make successful allocations in low-memory conditions that it would
experience varying stalls on bigger machines due to increased interrupts that
might be difficult to diagnose while not necessarily improving allocation
success rates. I also considered that if the machine is under pressure then
slab and slub may also be releasing pages of the same order and effectively
recycling their pages without depending on IPIs.
> Lets run some tests and see
> how it affect the issues that we are seeing.
>
Perfect, thanks.
--
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 15:06 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
2010-09-09 14:32 ` Christoph Lameter
2010-09-09 15:05 ` Mel Gorman [this message]
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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