From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <cl@linux.com>
Cc: npiggin@kernel.dk, Pekka Enberg <penberg@cs.helsinki.fi>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, Andi Kleen <andi@firstfloor.org>
Subject: Re: vmscan: Do not run shrinkers for zones other than ZONE_NORMAL
Date: Thu, 21 Oct 2010 13:14:28 -0700 [thread overview]
Message-ID: <20101021131428.f2f7214a.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1010211455100.30295@router.home>
On Thu, 21 Oct 2010 15:03:32 -0500 (CDT)
Christoph Lameter <cl@linux.com> wrote:
> On Thu, 21 Oct 2010, Andrew Morton wrote:
>
> > The patch doesn't patch direct reclaim, in do_try_to_free_pages(). How
> > come?
>
> Direct reclaim does not run node specific shrink_slab. Direct reclaim does
> a general pass after the individual zones have been shrunk.
>
> > OK, maybe this. Suppose we have a machine with 800M lowmem and 200M
> > highmem. And suppose the lowmem region is stuffed full of clean
> > icache/dcache. A __GFP_HIGHMEM allocation should put pressure on
> > lowmem to get some of those pages back. What we don't want to do is to
> > keep on reclaiming the highmem zone and allocating pages from there,
> > because the machine would effectively end up with only 200M available
> > for pagecache.
>
> Shrinker reclaim is not zone specific. It either occurs on a node or on
> the system as a whole. A failure of HIGHMEM allocation in the direct
> reclaim path will result in shrinkers being called with NO_NUMA_NODE and
> therefore global reclaim will take place everywhere.
>
> Per node reclaim occurs from kswapd and covers all zones of that node.
>
> > Please convince us that your patch doesn't screw up zone balancing?
>
> There are no slab allocations in HIGHMEM or MOVABLE. Nothing to balance
> there.
>
The patch changes balance_pgdat() to not shrink slab when inspecting
the highmem zone. It will therefore change zone balancing behaviour on
a humble 1G laptop, will it not?
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next prev parent reply other threads:[~2010-10-21 20:15 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-21 17:59 Christoph Lameter
2010-10-21 18:00 ` shrinkers: Add node to indicate where to target shrinking Christoph Lameter
2010-10-21 18:12 ` Andi Kleen
2010-10-21 20:57 ` David Rientjes
2010-10-21 21:07 ` Christoph Lameter
2010-10-22 13:27 ` Andi Kleen
2010-10-21 23:58 ` Nick Piggin
2010-10-22 12:12 ` Andi Kleen
2010-10-22 15:55 ` Christoph Hellwig
2010-10-22 16:32 ` Christoph Lameter
2010-10-24 1:42 ` Nick Piggin
2010-10-25 0:57 ` KOSAKI Motohiro
2010-10-25 14:59 ` Christoph Lameter
2010-11-09 4:03 ` Nick Piggin
2010-10-22 16:46 ` Andi Kleen
2010-10-24 1:31 ` Nick Piggin
2010-11-14 2:26 ` Michel Lespinasse
2010-11-14 7:10 ` KOSAKI Motohiro
2010-11-14 11:05 ` Michel Lespinasse
2010-11-15 0:29 ` KOSAKI Motohiro
2010-10-21 18:13 ` vmscan: Do not run shrinkers for zones other than ZONE_NORMAL Andi Kleen
2010-10-21 18:22 ` Christoph Lameter
2010-10-21 18:27 ` Christoph Lameter
2010-10-21 18:33 ` Andi Kleen
2010-10-21 20:48 ` David Rientjes
2010-10-21 20:54 ` Christoph Lameter
2010-10-21 19:40 ` Andrew Morton
2010-10-21 20:03 ` Christoph Lameter
2010-10-21 20:14 ` Andrew Morton [this message]
2010-10-21 20:28 ` Christoph Lameter
2010-10-21 20:36 ` Andrew Morton
2010-10-21 20:49 ` Christoph Lameter
2010-10-21 20:59 ` Andrew Morton
2010-10-21 21:13 ` Christoph Lameter
2010-10-21 21:21 ` Andrew Morton
2010-10-21 23:04 ` Christoph Lameter
2010-10-21 23:56 ` Nick Piggin
2010-10-22 1:37 ` KOSAKI Motohiro
2010-10-22 14:06 ` Christoph Lameter
2010-10-24 1:37 ` Nick Piggin
2010-10-25 1:22 ` KOSAKI Motohiro
2010-10-25 15:07 ` Christoph Lameter
2010-10-26 2:52 ` KOSAKI Motohiro
2010-10-26 12:42 ` KOSAKI Motohiro
2010-10-26 13:10 ` Christoph Lameter
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