Re: [PATCH 0/3] Reduce system overhead of automatic NUMA balancing

From: Dave Chinner
Date: Tue Mar 24 2015 - 07:51:51 EST


On Mon, Mar 23, 2015 at 12:24:00PM +0000, Mel Gorman wrote:
> These are three follow-on patches based on the xfsrepair workload Dave
> Chinner reported was problematic in 4.0-rc1 due to changes in page table
> management -- https://lkml.org/lkml/2015/3/1/226.
>
> Much of the problem was reduced by commit 53da3bc2ba9e ("mm: fix up numa
> read-only thread grouping logic") and commit ba68bc0115eb ("mm: thp:
> Return the correct value for change_huge_pmd"). It was known that the performance
> in 3.19 was still better even if is far less safe. This series aims to
> restore the performance without compromising on safety.
>
> Dave, you already tested patch 1 on its own but it would be nice to test
> patches 1+2 and 1+2+3 separately just to be certain.

3.19 4.0-rc4 +p1 +p2 +p3
mm_migrate_pages 266,750 572,839 558,632 223,706 201,429
run time 4m54s 7m50s 7m20s 5m07s 4m31s

numa stats form p1+p2:

numa_hit 8436537
numa_miss 0
numa_foreign 0
numa_interleave 30765
numa_local 8409240
numa_other 27297
numa_pte_updates 46109698
numa_huge_pte_updates 0
numa_hint_faults 44756389
numa_hint_faults_local 11841095
numa_pages_migrated 4868674
pgmigrate_success 4868674
pgmigrate_fail 0


numa stats form p1+p2+p3:

numa_hit 6991596
numa_miss 0
numa_foreign 0
numa_interleave 10336
numa_local 6983144
numa_other 8452
numa_pte_updates 24460492
numa_huge_pte_updates 0
numa_hint_faults 23677262
numa_hint_faults_local 5952273
numa_pages_migrated 3557928
pgmigrate_success 3557928
pgmigrate_fail 0

OK, the summary with all patches applied:

config 3.19 4.0-rc1 4.0-rc4 4.0-rc5+
defaults 8m08s 9m34s 9m14s 6m57s
-o ag_stride=-1 4m04s 4m38s 4m11s 4m06s
-o bhash=101073 6m04s 17m43s 7m35s 6m13s
-o ag_stride=-1,bhash=101073 4m54s 9m58s 7m50s 4m31s

So it looks like the patch set fixes the remaining regression and in
2 of the four cases actually improves performance....

Thanks, Linus and Mel, for tracking this tricky problem down!

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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