From: Vlastimil Babka <vbabka@suse.cz>
To: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
mgorman@techsingularity.net, Michal Hocko <mhocko@kernel.org>,
ying.huang@intel.com, s.priebe@profihost.ag,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
alex.williamson@redhat.com, lkp@01.org, kirill@shutemov.name,
Andrew Morton <akpm@linux-foundation.org>,
zi.yan@cs.rutgers.edu, Linux-MM layout <linux-mm@kvack.org>
Subject: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression
Date: Fri, 14 Dec 2018 22:33:42 +0100 [thread overview]
Message-ID: <0700f5c3-66a8-338a-0ba0-2231cc3bb637@suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.21.1812141244450.186427@chino.kir.corp.google.com>
On 12/14/18 10:04 PM, David Rientjes wrote:
> On Wed, 12 Dec 2018, Vlastimil Babka wrote:
...
> Reclaim likely could be deterministically useful if we consider a redesign
> of how migration sources and targets are determined in compaction.
>
> Has anybody tried a migration scanner that isn't linearly based, rather
> finding the highest-order free page of the same migratetype, iterating the
> pages of its pageblock, and using this to determine whether the actual
> migration will be worthwhile or not?
Not exactly that AFAIK, but a year ago in my series [1] patch 6 made
migration scanner 'prescan' the block of requested order before actually
trying to isolate anything for migration.
> I could imagine pageblock_skip being
> repurposed for this as the heuristic.
>
> Finding migration targets would be more tricky, but if we iterate the
> pages of the pageblock for low-order free pages and find them to be mostly
> used, that seems more appropriate than just pushing all memory to the end
> of the zone?
Agree. That was patch 8/8 of the same series [1].
> It would be interesting to know if anybody has tried using the per-zone
> free_area's to determine migration targets and set a bit if it should be
> considered a migration source or a migration target. If all pages for a
> pageblock are not on free_areas, they are fully used.
Repurposing/adding a new pageblock bit was in my mind to help multiple
compactors not undo each other's work in the scheme where there's no
free page scanner, but I didn't implement it yet.
>>> otherwise we fail and defer because it wasn't able
>>> to make a hugepage available.
>>
>> Note that THP fault compaction doesn't actually defer itself, which I
>> think is a weakness of the current implementation and hope that patch 3
>> in my series from yesterday [1] can address that. Because defering is
>> the general feedback mechanism that we have for suppressing compaction
>> (and thus associated reclaim) in cases it fails for any reason, not just
>> the one you mention. Instead of inspecting failure conditions in detail,
>> which would be costly, it's a simple statistical approach. And when
>> compaction is improved to fail less, defering automatically also happens
>> less.
>>
>
> I couldn't get the link to work, unfortunately, I don't think the patch
> series made it to LKML :/ I do see it archived for linux-mm, though, so
> I'll take a look, thanks!
Yeah I forgot to Cc: LKML, but you were also in direct To: so you should
have received them directly. Also the abovementioned series, but that's
year ago. My fault for not returning to it after being done with the
Meltdown fun. I hope to do that soon.
[1] https://marc.info/?l=linux-mm&m=151315560308753
>> [1] https://lkml.kernel.org/r/20181211142941.20500-1-vbabka@suse.cz
>>
next prev parent reply other threads:[~2018-12-14 21:36 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
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 [this message]
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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