linux-kernel - Re: [PATCH] vmscan: limit concurrent reclaimers in shrink

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Mon, 14 Dec 2009 17:19:44 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Larry Woodman <lwoodman@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>, Rik van Riel <riel@...hat.com>,
	kosaki.motohiro@...fujitsu.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	aarcange@...hat.com
Subject: Re: [PATCH] vmscan: limit concurrent reclaimers in shrink_zone

On Mon, Dec 14, 2009 at 09:23:19AM -0500, Larry Woodman wrote:
> On Mon, 2009-12-14 at 14:08 +0100, Andi Kleen wrote:
> > Rik van Riel <riel@...hat.com> writes:
> > 
> > > +max_zone_concurrent_reclaim:
> > > +
> > > +The number of processes that are allowed to simultaneously reclaim
> > > +memory from a particular memory zone.
> > > +
> > > +With certain workloads, hundreds of processes end up in the page
> > > +reclaim code simultaneously.  This can cause large slowdowns due
> > > +to lock contention, freeing of way too much memory and occasionally
> > > +false OOM kills.
> > > +
> > > +To avoid these problems, only allow a smaller number of processes
> > > +to reclaim pages from each memory zone simultaneously.
> > > +
> > > +The default value is 8.
> > 
> > I don't like the hardcoded number. Is the same number good for a 128MB
> > embedded system as for as 1TB server?  Seems doubtful.
> > 
> > This should be perhaps scaled with memory size and number of CPUs?
> 
> Remember this a per-zone number.

A zone could be 64MB or 32GB. And the system could have 1 or 1024 CPUs.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
--
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/