From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: Xen Platform QoS design discussion
Date: Fri, 30 May 2014 10:10:52 +0100
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To: Jan Beulich <jbeulich@suse.com>
Cc: george.dunlap@eu.citrix.com, andrew.cooper3@citrix.com, will.auld@intel.com, xen-devel@lists.xen.org, dongxiao.xu@intel.com, jun.nakajima@intel.com
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On Thu, 2014-05-29 at 10:11 +0100, Jan Beulich wrote:
> >>> "Xu, Dongxiao" <dongxiao.xu@intel.com> 05/29/14 9:31 AM >>>
> >Okay. If I understand correctly, you prefer to implement a pure MSR access
> >hypercall for one CPU, and put all other CQM things in libxc/libxl layer.
> 
> >In this case, if libvert/XenAPI is trying to query a domain's cache utilization
> >in the system (say 2 sockets), then it will trigger _two_ such MSR access
> >hypercalls for CPUs in the 2 different sockets.
> >If you are okay with this idea, I am going to implement it.
>  
> I am okay with it, but give it a couple of days before you start so that others
> can voice their opinions too.

Dom0 may not have a vcpu which is scheduled/schedulable on every socket.
scheduled it can probably deal with by doing awful sounding temporary
things to its affinity mask, but if it is not schedulable (e.g. due to
cpupools etc) then that sounds even harder to sort...

Ian.