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| author | Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> | 2014-08-28 19:34:34 +0100 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-09-26 11:51:54 +0200 |
| commit | c824c468fd7660207f10cd333b2a1fa188d533b0 (patch) | |
| tree | c0a8c925af27787eac160f7d621b2efcd393d42b /mm/compaction.c | |
| parent | 760265401f255337347c42bc8fb0b9c1c682d904 (diff) | |
| download | lwn-c824c468fd7660207f10cd333b2a1fa188d533b0.tar.gz lwn-c824c468fd7660207f10cd333b2a1fa188d533b0.zip | |
mm: get rid of unnecessary pageblock scanning in setup_zone_migrate_reserve
commit 943dca1a1fcbccb58de944669b833fd38a6c809b upstream.
Yasuaki Ishimatsu reported memory hot-add spent more than 5 _hours_ on
9TB memory machine since onlining memory sections is too slow. And we
found out setup_zone_migrate_reserve spent >90% of the time.
The problem is, setup_zone_migrate_reserve scans all pageblocks
unconditionally, but it is only necessary if the number of reserved
block was reduced (i.e. memory hot remove).
Moreover, maximum MIGRATE_RESERVE per zone is currently 2. It means
that the number of reserved pageblocks is almost always unchanged.
This patch adds zone->nr_migrate_reserve_block to maintain the number of
MIGRATE_RESERVE pageblocks and it reduces the overhead of
setup_zone_migrate_reserve dramatically. The following table shows time
of onlining a memory section.
Amount of memory | 128GB | 192GB | 256GB|
---------------------------------------------
linux-3.12 | 23.9 | 31.4 | 44.5 |
This patch | 8.3 | 8.3 | 8.6 |
Mel's proposal patch | 10.9 | 19.2 | 31.3 |
---------------------------------------------
(millisecond)
128GB : 4 nodes and each node has 32GB of memory
192GB : 6 nodes and each node has 32GB of memory
256GB : 8 nodes and each node has 32GB of memory
(*1) Mel proposed his idea by the following threads.
https://lkml.org/lkml/2013/10/30/272
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reported-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'mm/compaction.c')
0 files changed, 0 insertions, 0 deletions