From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [RFC PATCH 0/7] Intel Cache Monitoring: Current Status and Future Opportunities Date: Wed, 8 Apr 2015 09:53:48 +0100 Message-ID: <5524EC9C.1040900@citrix.com> References: <20150404020423.22875.23590.stgit@Solace.station> <5523B0FB.8020509@citrix.com> <1428412199.5671.94.camel@citrix.com> <20150408055916.GF3404@pengc-linux.bj.intel.com> <1428481389.5671.98.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1428481389.5671.98.camel@citrix.com> 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 , "chao.p.peng@linux.intel.com" Cc: Ian Campbell , Wei Liu , George Dunlap , "JBeulich@suse.com" , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 08/04/15 09:23, Dario Faggioli wrote: > On Wed, 2015-04-08 at 13:59 +0800, Chao Peng wrote: > >>> Mostly, I was curious to learn why that is not reflected in the current >>> implementation, i.e., whether there are any reasons why we should not >>> take advantage of per-socketness of RMIDs, as reported by SDM, as that >>> can greatly help mitigating RMID shortage in the per-CPU/core/socket >>> configuration (in general, actually, but it's per-cpu that I'm >>> interested in). >> Andrew is right, RMID is a per-socket property. One reason it's not used >> in current implementation, I think, is the fact that max_rmid is >> normally the same among sockets, though they can be different in theory. >> So the same RMID is targeted for all the sockets. But per-socketness of >> RMIDs can be used anyway. >> > Yeah, but rather than to the maximum number of available RMIDs, what I'm > much interested in is whether I can use _the_ _same_ RMID for different > cores, if they belong to different sockets. AFAIUI, it is possible, is > that correct? It is perfectly possible to track the same logical resource using different RMIDs on different sockets. ~Andrew > >>> All true. And in fact, how and how frequent data should be gathered >>> remains to be decided (as said in the document). I was thinking more to >>> some periodic sampling, rather than to throw handfuls of rdmsr/wrmsr >>> against the code that makes scheduling decisions! :-D >> Due to current hardware limitations and in the case of scheduling improvement, >> periodic sampling sounds a feasible direction to me. >> > Good to know, thanks. > > Regards, > Dario