Re: [PATCH] xen: avoid updating node affinity twice when removing a CPU from a cpupool

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

On 03/12/2015 01:45 PM, Dario Faggioli wrote:
> On Wed, 2015-03-11 at 16:04 +0000, Dario Faggioli wrote:
>> On Wed, 2015-03-11 at 15:01 +0000, George Dunlap wrote:
> 
>>> It looks like domain_update_node_affinity() is already called for each
>>> domain in the cpupool in cpu_disable_scheduler().  It doesn't look like
>>> there should be a need to call it twice.  Can we just remove the call to
>>> domain_update_node_affinity() in cpupool_unassign_cpu() and not add it back?
>>>
>> Mmm.. true, actually.
>>
>> I'll send a patch to that effect.
>>
> Patch below, and attached. However, I think the correct thing to do
> would be to just revert 93be8285 "update domU's node-affinity on the
> cpupool_unassign_cpu() path", wouldn't it?

Funny you should mention that... one of the things I was thinking of
suggesting was trying to move the domain_update_node_affinity() out of
cpupool.c and into schedule.c, somewhere on the path that brings up a
cpu or assigns it to a pool, specifically so that the lack of symmetry
didn't trip anybody up.  But at a quick glance I couldn't find a likely
candidate.

Now that I find out it already *has* tripped someone up, I think we had
definitely better do something about it. :-)

Let me take a look and see what seems sensible...

 -George