linux-kernel - Re: [PATCH] slub: Avoid direct compaction if possible

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 14 Jun 2013 16:08:02 +0000
From:	Christoph Lameter <cl@...two.org>
To:	Roman Gushchin <klamm@...dex-team.ru>
cc:	Pekka Enberg <penberg@...nel.org>, mpm@...enic.com,
	akpm@...ux-foundation.org, mgorman@...e.de,
	David Rientjes <rientjes@...gle.com>, glommer@...il.com,
	hannes@...xchg.org, minchan@...nel.org, jiang.liu@...wei.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slub: Avoid direct compaction if possible

On Fri, 14 Jun 2013, Roman Gushchin wrote:

> But there is an actual problem, that this patch solves.
> Sometimes I saw the following issue on some machines:
> all CPUs are performing compaction, system time is about 80%,
> system is completely unreliable. It occurs only on machines
> with specific workload (distributed data storage system, so,
> intensive disk i/o is performed). A system can fall into
> this state fast and unexpectedly or by progressive degradation.

Well that is not a slab allocator specific issue but related to compaction
concurrency. Likely cache line contention is causing a severe slowday. But
that issue could be triggered by any subsystem that does lots of memory
allocations. I would suggest that we try to address the problem in the
compaction logic rather than modifying allocators.

Mel?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/