From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: RFC: automatic NUMA placement Date: Fri, 17 Sep 2010 08:26:24 +0200 Message-ID: <4C930A10.1090301@ts.fujitsu.com> References: <4C921DDF.6020809@ts.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 09/16/10 17:52, Dan Magenheimer wrote: > 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. Took a while to find it, but hg log helped :-) Patch: http://xenbits.xensource.com/staging/xen-unstable.hg?diff/b58180cf8ab8/tools/python/xen/xend/XendDomainInfo.py Discussion: http://lists.xensource.com/archives/html/xen-devel/2008-02/msg00883.html > >> -----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