linux-kernel - Re: [PATCH v2] KSM: numa awareness sysfs knob

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

Date:	Fri, 29 Jun 2012 15:50:31 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Petr Holasek <pholasek@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Chris Wright <chrisw@...s-sol.org>,
	Izik Eidus <izik.eidus@...ellosystems.com>,
	Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Anton Arapov <anton@...hat.com>
Subject: Re: [PATCH v2] KSM: numa awareness sysfs knob

On Fri, 29 Jun 2012, Andrew Morton wrote:

> > I've tested this patch on numa machines with 2, 4 and 8 nodes and
> > measured speed of memory access inside of KVM guests with memory pinned
> > to one of nodes with this benchmark:
> > 
> > http://pholasek.fedorapeople.org/alloc_pg.c
> > 
> > Population standard deviations of access times in percentage of average
> > were following:
> > 
> > merge_nodes=1
> > 2 nodes 1.4%
> > 4 nodes 1.6%
> > 8 nodes	1.7%
> > 
> > merge_nodes=0
> > 2 nodes	1%
> > 4 nodes	0.32%
> > 8 nodes	0.018%
> 
> ooh, numbers!  Thanks.
> 

Ok, the standard deviation increases when merging pages from nodes with 
remote distance, that makes sense.  But if that's true, then you would 
restrict either the entire application to local memory with mempolicies or 
cpusets, or you would use mbind() to restrict this memory to that set of 
nodes already so that accesses, even with ksm merging, would have 
affinity.
--
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/