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From: Dan Magenheimer <dan.magenheimer@ORACLE.COM>
To: Juergen Gross <juergen.gross@ts.fujitsu.com>,
	xen-devel@lists.xensource.com
Subject: RE: RFC: automatic NUMA placement
Date: Thu, 16 Sep 2010 08:52:07 -0700 (PDT)	[thread overview]
Message-ID: <ebc64da4-e656-4c50-bdd6-799807d8078f@default> (raw)
In-Reply-To: <4C921DDF.6020809@ts.fujitsu.com>

I am in favor of this being optional rather than default.
It is another case of the tradeoff between performance
and flexibility that I have ranted about several times
on xen-devel, and Xen's policy seems to be fairly random
(sometimes Xen chooses performance over flexibility and
sometimes the opposite).

I went looking through xen-devel archives for a previous
discussion on this (and to find when the code got added)
but couldn't find it... if you have links to the patch
and discussion, please post.

> -----Original Message-----
> From: Juergen Gross [mailto:juergen.gross@ts.fujitsu.com]
> Sent: Thursday, September 16, 2010 7:39 AM
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] RFC: automatic NUMA placement
> 
> Hi,
> 
> I just stumbled upon the automatic pinning of vcpus on domain creation
> in
> case of NUMA.
> This behaviour is questionable IMO, as it breaks correct handling of
> scheduling weights on NUMA machines.
> I would suggest to switch this feature off per default and make it a
> configuration option of xend. It would make sense, however, to change
> cpu pool
> processor allocation to be NUMA-aware.
> Switching NUMA off via boot option would remove NUMA-optimized memory
> allocation, which would be sub-optimal :-)
> 
> What do you think?
> 
> 
> Juergen
> 
> --
> Juergen Gross                 Principal Developer Operating Systems
> TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
> Fujitsu Technology Solutions              e-mail:
> juergen.gross@ts.fujitsu.com
> Domagkstr. 28                           Internet: ts.fujitsu.com
> D-80807 Muenchen                 Company details:
> ts.fujitsu.com/imprint.html
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

  reply	other threads:[~2010-09-16 15:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-16 13:38 RFC: automatic NUMA placement Juergen Gross
2010-09-16 15:52 ` Dan Magenheimer [this message]
2010-09-17  6:26   ` Juergen Gross
2010-09-27 21:46 ` Andre Przywara
2010-09-28  4:48   ` Juergen Gross

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