On Tue, Mar 24, 2015 at 10:51:41PM +1100, Dave Chinner wrote: > 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 > Excellent, this is in line with predictions and roughly matches what I was seeing on bare metal + real NUMA + spinning disk instead of KVM + fake NUMA + SSD. Editting slightly; > numa stats form p1+p2: numa_pte_updates 46109698 > numa stats form p1+p2+p3: numa_pte_updates 24460492 The big drop in PTE updates matches what I expected -- migration failures should not lead to increased scan rates which is what patch 3 fixes. I'm also pleased that there was not a drop in performance. > > 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.... > \o/ Linus, these three patches plus the small fixlet for pmd_mkyoung (to match pte_mkyoung) is already in Andrew's tree. I'm expecting it'll arrive to you before 4.0 assuming nothing else goes pear shaped. > Thanks, Linus and Mel, for tracking this tricky problem down! > Thanks Dave for persisting with this and collecting the necessary data. FWIW, I've marked the xfsrepair test case as a "large memory test". It'll take time before the test machines have historical data for it but in theory if this regresses again then I should spot it eventually. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>