On Wed, Jan 19, 2011 at 10:53 AM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
> On Wed, 19 Jan 2011, Minchan Kim wrote:
>
>> >
>> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> > --- a/mm/page_alloc.c
>> > +++ b/mm/page_alloc.c
>> > @@ -2034,6 +2034,18 @@ restart:
>> > */
>> > alloc_flags = gfp_to_alloc_flags(gfp_mask);
>> >
>> > + /*
>> > + * If preferred_zone cannot be allocated from in this context, find the
>> > + * first allowable zone instead.
>> > + */
>> > + if ((alloc_flags & ALLOC_CPUSET) &&
>> > + !cpuset_zone_allowed_softwall(preferred_zone, gfp_mask)) {
>> > + first_zones_zonelist(zonelist, high_zoneidx,
>> > + &cpuset_current_mems_allowed, &preferred_zone);
>>
>> This patch is one we need. but I have a nitpick.
>> I am not familiar with CPUSET so I might be wrong.
>>
>> I think it could make side effect of statistics of ZVM on
>> buffered_rmqueue since you intercept and change preferred_zone.
>> It could make NUMA_HIT instead of NUMA_MISS.
>> Is it your intention?
>>
>
> It depends on the semantics of NUMA_MISS: if no local nodes are allowed by
> current's cpuset (a pretty poor cpuset config :), then it seems logical
> that all allocations would be a miss.
It does make sense to me but I delegate the decision to Christoph who is author.
And please write down this behavior change into changelog. :)
Thanks David.
--
Kind regards,
Minchan Kim
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