Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page arrival

From	Dave Hansen <dave.hansen@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page arrival
Date	2016-06-08 18:40 +0200
Message-ID	<rHOGl-2xG-15@gated-at.bofh.it> (permalink)
References	<rHMOe-1mm-23@gated-at.bofh.it> <rHNKh-1Yh-3@gated-at.bofh.it> <rHOdj-2nA-13@gated-at.bofh.it>
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On 06/08/2016 09:06 AM, Michal Hocko wrote:
>> > Do we have any statistics that tell us how many pages are sitting the
>> > lru pvecs?  Although this helps the problem overall, don't we still have
>> > a problem with memory being held in such an opaque place?
> Is it really worth bothering when we are talking about 56kB per CPU
> (after this patch)?

That was the logic why we didn't have it up until now: we didn't
*expect* it to get large.  A code change blew it up by 512x, and we had
no instrumentation to tell us where all the memory went.

I guess we don't have any other ways to group pages than compound pages,
and _that_ one is covered now... for one of the 5 classes of pvecs.

Is there a good reason we don't have to touch the other 4 pagevecs, btw?

Thread

[PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page arrival Lukasz Odzioba <lukasz.odzioba@intel.com> - 2016-06-08 16:40 +0200
  Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Michal Hocko <mhocko@kernel.org> - 2016-06-08 17:10 +0200
    RE: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival "Odzioba, Lukasz" <lukasz.odzioba@intel.com> - 2016-06-09 10:10 +0200
  Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Dave Hansen <dave.hansen@intel.com> - 2016-06-08 17:40 +0200
    Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Michal Hocko <mhocko@kernel.org> - 2016-06-08 18:10 +0200
      Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Dave Hansen <dave.hansen@intel.com> - 2016-06-08 18:40 +0200
        Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Michal Hocko <mhocko@kernel.org> - 2016-06-09 14:30 +0200
    RE: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival "Odzioba, Lukasz" <lukasz.odzioba@intel.com> - 2016-06-09 11:00 +0200
      Re: [PATCH 1/1] mm/swap.c: flush lru_add pvecs on compound page  arrival Dave Hansen <dave.hansen@intel.com> - 2016-06-09 17:50 +0200

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