Re: MAP_POPULATE vs. MADV_HUGEPAGES

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: MAP_POPULATE vs. MADV_HUGEPAGES
Date	2017-03-16 16:10 +0100
Message-ID	<tlFco-97-65@gated-at.bofh.it> (permalink)
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On Thu 16-03-17 16:56:34, Avi Kivity wrote:
> On 03/16/2017 04:48 PM, Michal Hocko wrote:
> >On Thu 16-03-17 15:26:54, Avi Kivity wrote:
[...]
> >>>What is the THP defrag mode
> >>>(/sys/kernel/mm/transparent_hugepage/defrag)?
> >>The default (always).
> >the default has changed since then because the THP faul latencies were
> >just too large. Currently we only allow madvised VMAs to go stall and
> >even then we try hard to back off sooner rather than later. See
> >444eb2a449ef ("mm: thp: set THP defrag by default to madvise and add a
> >stall-free defrag option") merged in 4.4
> 
> I see, thanks.  So the 4.4 behavior is better mostly due to not trying so
> hard.

Please note there were many other patches in the compaction code as
well.
-- 
Michal Hocko
SUSE Labs

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MAP_POPULATE vs. MADV_HUGEPAGES Avi Kivity <avi@scylladb.com> - 2017-03-15 18:00 +0100
  Re: MAP_POPULATE vs. MADV_HUGEPAGES Michal Hocko <mhocko@kernel.org> - 2017-03-16 13:40 +0100
    Re: MAP_POPULATE vs. MADV_HUGEPAGES Avi Kivity <avi@scylladb.com> - 2017-03-16 14:30 +0100
      Re: MAP_POPULATE vs. MADV_HUGEPAGES Michal Hocko <mhocko@kernel.org> - 2017-03-16 15:50 +0100
        Re: MAP_POPULATE vs. MADV_HUGEPAGES Avi Kivity <avi@scylladb.com> - 2017-03-16 16:00 +0100
          Re: MAP_POPULATE vs. MADV_HUGEPAGES Michal Hocko <mhocko@kernel.org> - 2017-03-16 16:10 +0100

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