From: Michal Hocko <mhocko@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: rong.a.chen@intel.com, Andrea Arcangeli <aarcange@redhat.com>,
s.priebe@profihost.ag, alex.williamson@redhat.com,
mgorman@techsingularity.net, zi.yan@cs.rutgers.edu,
Vlastimil Babka <vbabka@suse.cz>,
rientjes@google.com, kirill@shutemov.name,
Andrew Morton <akpm@linux-foundation.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
lkp@01.org
Subject: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression
Date: Tue, 27 Nov 2018 19:21:37 +0100 [thread overview]
Message-ID: <20181127182137.GE6923@dhcp22.suse.cz> (raw)
In-Reply-To: <20181127181727.GD6923@dhcp22.suse.cz>
On Tue 27-11-18 19:17:27, Michal Hocko wrote:
> On Tue 27-11-18 09:08:50, Linus Torvalds wrote:
> > On Mon, Nov 26, 2018 at 10:24 PM kernel test robot
> > <rong.a.chen@intel.com> wrote:
> > >
> > > FYI, we noticed a -61.3% regression of vm-scalability.throughput due
> > > to commit ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for
> > > MADV_HUGEPAGE mappings")
> >
> > Well, that's certainly noticeable and not good.
> >
> > Andrea, I suspect it might be causing fights with auto numa migration..
> >
> > Lots more system time, but also look at this:
> >
> > > 1122389 ± 9% +17.2% 1315380 ± 4% proc-vmstat.numa_hit
> > > 214722 ± 5% +21.6% 261076 ± 3% proc-vmstat.numa_huge_pte_updates
> > > 1108142 ± 9% +17.4% 1300857 ± 4% proc-vmstat.numa_local
> > > 145368 ± 48% +63.1% 237050 ± 17% proc-vmstat.numa_miss
> > > 159615 ± 44% +57.6% 251573 ± 16% proc-vmstat.numa_other
> > > 185.50 ± 81% +8278.6% 15542 ± 40% proc-vmstat.numa_pages_migrated
> >
> > Should the commit be reverted? Or perhaps at least modified?
>
> Well, the commit is trying to revert to the behavior before
> 5265047ac301 because there are real usecases that suffered from that
> change and bug reports as a result of that.
>
> will-it-scale is certainly worth considering but it is an artificial
> testcase. A higher NUMA miss rate is an expected side effect of the
> patch because the fallback to a different NUMA node is more likely. The
> __GFP_THISNODE side effect is basically introducing node-reclaim
> behavior for THPages. Another thing is that there is no good behavior
> for everybody. Reclaim locally vs. THP on a remote node is hard to
> tell by default. We have discussed that at length and there were some
> conclusions. One of them is that we need a numa policy to tell whether
> a expensive localility is preferred over remote allocation. Also we
> definitely need a better pro-active defragmentation to allow larger
> pages on a local node. This is a work in progress and this patch is a
> stop gap fix.
Btw. the associated discussion is http://lkml.kernel.org/r/20180925120326.24392-1-mhocko@kernel.org
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-11-27 18:21 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 6:25 [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression kernel test robot
2018-11-27 17:08 ` Linus Torvalds
2018-11-27 18:17 ` Michal Hocko
2018-11-27 18:21 ` Michal Hocko [this message]
2018-11-27 19:05 ` Vlastimil Babka
2018-11-27 19:16 ` Vlastimil Babka
2018-11-27 20:57 ` Andrea Arcangeli
2018-11-27 22:50 ` Linus Torvalds
2018-11-28 6:30 ` Michal Hocko
2018-11-28 3:20 ` Huang, Ying
2018-11-28 16:48 ` Linus Torvalds
2018-11-28 18:39 ` Andrea Arcangeli
2018-11-28 23:10 ` David Rientjes
2018-12-03 18:01 ` Linus Torvalds
2018-12-03 18:14 ` Michal Hocko
2018-12-03 18:19 ` Linus Torvalds
2018-12-03 18:30 ` Michal Hocko
2018-12-03 18:45 ` Linus Torvalds
2018-12-03 18:59 ` Michal Hocko
2018-12-03 19:23 ` Andrea Arcangeli
2018-12-03 20:26 ` David Rientjes
2018-12-03 19:28 ` Linus Torvalds
2018-12-03 20:12 ` Andrea Arcangeli
2018-12-03 20:36 ` David Rientjes
2018-12-03 22:04 ` Linus Torvalds
2018-12-03 22:27 ` Linus Torvalds
2018-12-03 22:57 ` David Rientjes
2018-12-04 9:22 ` Vlastimil Babka
2018-12-04 10:45 ` Mel Gorman
2018-12-05 0:47 ` David Rientjes
2018-12-05 9:08 ` Michal Hocko
2018-12-05 10:43 ` Mel Gorman
2018-12-05 11:43 ` Michal Hocko
2018-12-05 10:06 ` Mel Gorman
2018-12-05 20:40 ` Andrea Arcangeli
2018-12-05 21:59 ` David Rientjes
2018-12-06 0:00 ` Andrea Arcangeli
2018-12-05 22:03 ` Linus Torvalds
2018-12-05 22:12 ` David Rientjes
2018-12-05 23:36 ` Andrea Arcangeli
2018-12-05 23:51 ` Linus Torvalds
2018-12-06 0:58 ` Linus Torvalds
2018-12-06 9:14 ` MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression) Michal Hocko
2018-12-06 23:49 ` David Rientjes
2018-12-07 7:34 ` Michal Hocko
2018-12-07 4:31 ` Linus Torvalds
2018-12-07 7:49 ` Michal Hocko
2018-12-07 9:06 ` Vlastimil Babka
2018-12-07 23:15 ` David Rientjes
2018-12-06 23:43 ` [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression David Rientjes
2018-12-07 4:01 ` Linus Torvalds
2018-12-10 0:29 ` David Rientjes
2018-12-10 4:49 ` Andrea Arcangeli
2018-12-12 0:37 ` David Rientjes
2018-12-12 9:50 ` Michal Hocko
2018-12-12 17:00 ` Andrea Arcangeli
2018-12-14 11:32 ` Michal Hocko
2018-12-12 10:14 ` Vlastimil Babka
2018-12-14 21:04 ` David Rientjes
2018-12-14 21:33 ` Vlastimil Babka
2018-12-21 22:18 ` David Rientjes
2018-12-22 12:08 ` Mel Gorman
2018-12-14 23:11 ` Mel Gorman
2018-12-21 22:15 ` David Rientjes
2018-12-12 10:44 ` Andrea Arcangeli
2019-04-15 11:48 ` Michal Hocko
2018-12-06 0:18 ` David Rientjes
2018-12-06 0:54 ` Andrea Arcangeli
2018-12-06 9:23 ` Vlastimil Babka
2018-12-03 20:39 ` David Rientjes
2018-12-03 21:25 ` Michal Hocko
2018-12-03 21:53 ` David Rientjes
2018-12-04 8:48 ` Michal Hocko
2018-12-05 0:07 ` David Rientjes
2018-12-05 10:18 ` Michal Hocko
2018-12-05 19:16 ` David Rientjes
2018-11-27 7:23 kernel test robot
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