From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH v2 16/16] libxl: automatic NUMA placement affects soft affinity Date: Thu, 14 Nov 2013 17:49:23 +0000 Message-ID: <52850D23.9000809@eu.citrix.com> References: <20131113190852.18086.5437.stgit@Solace> <20131113191334.18086.72275.stgit@Solace> <5284F435.7080106@eu.citrix.com> <1384447720.29902.180.camel@Abyss> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1384447720.29902.180.camel@Abyss> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Dario Faggioli Cc: Marcus Granado , Keir Fraser , Ian Campbell , Li Yechen , Andrew Cooper , Juergen Gross , Ian Jackson , xen-devel@lists.xen.org, Jan Beulich , Justin Weaver , Matt Wilson , Elena Ufimtseva List-Id: xen-devel@lists.xenproject.org On 11/14/2013 04:48 PM, Dario Faggioli wrote: > On gio, 2013-11-14 at 16:03 +0000, George Dunlap wrote: >> On 13/11/13 19:13, Dario Faggioli wrote: >>> vCPU soft affinity and NUMA-aware scheduling does not have >>> to be related. However, soft affinity is how NUMA-aware >>> scheduling is actually implemented, and therefore, by default, >>> the results of automatic NUMA placement (at VM creation time) >>> are also used to set the soft affinity of all the vCPUs of >>> the domain. >>> >>> Of course, this only happens if automatic NUMA placement is >>> enabled and actually takes place (for instance, if the user >>> does not specify any hard and soft affiniy in the xl config >>> file). >>> >>> This also takes care of the vice-versa, i.e., don't trigger >>> automatic placement if the config file specifies either an >>> hard (the check for which was already there) or a soft (the >>> check for which is introduced by this commit) affinity. >> >> It looks like with this patch you set *both* hard and soft affinities >> when doing auto-numa placement. Would it make more sense to change it >> to setting only the soft affinity, and leaving the hard affinity to "any"? >> > Nope, it indeed sets only soft affinity after automatic placement, hard > affinity is left untouched. Oh, right -- dur, I had it in my head that you were setting hard affinities before this patch (and since I didn't see them removed I assumed they were still there.) But that's what we did sometime in ancient history, before the scheduler paid attention to the domain numa affinity. :-) That being the case, Acked-by: George Dunlap (If I have time I may come by and do a closer review later.) -George