From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Magenheimer Subject: RE: RFC: automatic NUMA placement Date: Thu, 16 Sep 2010 08:52:07 -0700 (PDT) Message-ID: References: <4C921DDF.6020809@ts.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4C921DDF.6020809@ts.fujitsu.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Juergen Gross , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org 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 >=20 > Hi, >=20 > 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 :-) >=20 > What do you think? >=20 >=20 > Juergen >=20 > -- > 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 >=20 > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel