From: Pavel Machek <pavel@ucw.cz>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>,
stable@kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Frans Pop <elendil@planet.nl>,
Jiri Kosina <jkosina@suse.cz>,
Sven Geggus <lists@fuchsschwanzdomain.de>,
Karol Lewandowski <karol.k.lewandowski@gmail.com>,
Tobias Oetiker <tobi@oetiker.ch>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Rik van Riel <riel@redhat.com>,
Christoph Lameter <cl@linux-foundation.org>,
Stephan von Krawczynski <skraw@ithnet.com>,
kernel-testers@vger.kernel.org
Subject: Re: [PATCH 2/3] page allocator: Do not allow interrupts to use ALLOC_HARDER
Date: Sat, 31 Oct 2009 21:11:59 +0100 [thread overview]
Message-ID: <20091031201158.GB29536@elf.ucw.cz> (raw)
In-Reply-To: <alpine.DEB.2.00.0910311248490.13829@chino.kir.corp.google.com>
On Sat 2009-10-31 12:51:14, David Rientjes wrote:
> On Sat, 31 Oct 2009, Pavel Machek wrote:
>
> > > Giving rt tasks access to memory reserves is necessary to reduce latency,
> > > the privilege does not apply to interrupts that subsequently get run on
> > > the same cpu.
> >
> > If rt task needs to allocate memory like that, then its broken,
> > anyway...
>
> Um, no, it's a matter of the kernel implementation. We allow such tasks
> to allocate deeper into reserves to avoid the page allocator from
> incurring a significant penalty when direct reclaim is required.
> Background reclaim has already commenced at this point in the
>slowpath.
But we can't guarantee that enough memory will be ready in the
reserves. So if realtime task relies on it, it is broken, and will
fail to meet its deadlines from time to time.
Pavel
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next prev parent reply other threads:[~2009-10-31 20:12 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-27 13:40 [PATCH 0/3] Reduce GFP_ATOMIC allocation failures, partial fix V3 Mel Gorman
2009-10-27 13:40 ` [PATCH 1/3] page allocator: Always wake kswapd when restarting an allocation attempt after direct reclaim failed Mel Gorman
2009-10-27 13:40 ` [PATCH 2/3] page allocator: Do not allow interrupts to use ALLOC_HARDER Mel Gorman
[not found] ` <1256650833-15516-3-git-send-email-mel-wPRd99KPJ+uzQB+pC5nmwQ@public.gmane.org>
2009-10-27 20:09 ` Andrew Morton
2009-10-27 21:12 ` David Rientjes
2009-10-31 18:40 ` Pavel Machek
2009-10-31 19:51 ` David Rientjes
2009-10-31 20:11 ` Pavel Machek [this message]
2009-10-31 21:19 ` David Rientjes
2009-10-31 22:29 ` Pavel Machek
2009-10-31 22:55 ` Rik van Riel
2009-11-01 7:35 ` Pavel Machek
2009-11-01 12:37 ` KOSAKI Motohiro
2009-11-01 14:44 ` Rik van Riel
2009-11-01 19:32 ` Pavel Machek
2009-11-02 16:38 ` Christoph Lameter
2009-10-31 23:59 ` Rik van Riel
2009-11-02 16:42 ` Christoph Lameter
2009-11-02 20:53 ` David Rientjes
2009-11-03 17:10 ` Christoph Lameter
2009-11-04 1:46 ` David Rientjes
2009-11-04 9:01 ` Pavel Machek
2009-11-09 10:11 ` Mel Gorman
2009-10-28 10:24 ` Mel Gorman
2009-10-27 13:40 ` [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit Mel Gorman
2009-10-27 18:18 ` Rik van Riel
2009-10-27 20:19 ` Andrew Morton
2009-10-28 3:54 ` KOSAKI Motohiro
2009-10-28 10:29 ` Mel Gorman
2009-10-28 19:47 ` Andrew Morton
2009-11-02 16:05 ` Mel Gorman
2009-11-02 17:32 ` Frans Pop
2009-11-02 17:38 ` Mel Gorman
2009-11-02 20:36 ` Mel Gorman
2009-11-03 22:01 ` Frans Pop
2009-11-03 22:08 ` Mel Gorman
2009-11-04 0:01 ` Frans Pop
2009-11-04 1:18 ` Mel Gorman
2009-11-04 2:05 ` Frans Pop
2009-11-04 2:08 ` Frans Pop
2009-11-04 15:48 ` Mel Gorman
2009-11-04 20:57 ` Frans Pop
2009-11-05 16:48 ` [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit (data on latencies available) Mel Gorman
2009-11-12 11:36 ` Frans Pop
2009-11-04 2:08 ` [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit Mel Gorman
2009-10-28 13:02 ` [PATCH 0/3] Reduce GFP_ATOMIC allocation failures, partial fix V3 Karol Lewandowski
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