From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Dunlap <george.dunlap@eu.citrix.com>
Subject: Re: [PATCH RESEND 05/12] xen: numa-sched: make space
 for per-vcpu node-affinity
Date: Tue, 5 Nov 2013 15:39:55 +0000
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To: Jan Beulich <JBeulich@suse.com>
Cc: MarcusGranado <Marcus.Granado@eu.citrix.com>, Justin Weaver <jtweaver@hawaii.edu>, Ian Campbell <Ian.Campbell@citrix.com>, Li Yechen <lccycc123@gmail.com>, Andrew Cooper <Andrew.Cooper3@citrix.com>, Dario Faggioli <dario.faggioli@citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Matt Wilson <msw@amazon.com>, xen-devel <xen-devel@lists.xenproject.org>, Daniel De Graaf <dgdegra@tycho.nsa.gov>, KeirFraser <keir@xen.org>, Elena Ufimtseva <ufimtseva@gmail.com>, Juergen Gross <juergen.gross@ts.fujitsu.com>
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On 11/05/2013 03:23 PM, Jan Beulich wrote:
>>>> On 05.11.13 at 16:11, George Dunlap <george.dunlap@eu.citrix.com> wrote:
>> Or, we could internally change the names to "cpu_hard_affinity" and
>> "cpu_soft_affinity", since that's effectively what the scheduler will
>> do.  It's possible someone might want to set soft affinities for some
>> other reason besides NUMA performance.
>
> I like that.

A potential problem with that is the "auto domain numa" thing.  In this 
patch, if the domain numa affinity is not set but vcpu numa affinity is, 
the domain numa affinity (which will be used to allocate memory for the 
domain) will be set based on the vcpu numa affinity.  That seems like a 
useful feature (though perhaps it's starting to violate the "policy 
should be in the tools" principle).  If we change this to just "hard 
affinity" and "soft affinity", we'll lose the natural logical connection 
there.  It might have impacts on how we end up doing vNUMA as well.  So 
I'm a bit torn ATM.

Dario, any thoughts?

  -George