Re: [PATCH v2 16/16] libxl: automatic NUMA placement affects soft affinity

[George Dunlap <george.dunlap@eu.citrix.com>]

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 <george.dunlap@eu.citrix.com>

(If I have time I may come by and do a closer review later.)

  -George