Changelog since V1 o Dropped kswapd related patch, basically a no-op and regresses if fixed (minchan) o Expanded changelogs a little Allocation success rates have been far lower since 3.4 due to commit [fe2c2a10: vmscan: reclaim at order 0 when compaction is enabled]. This commit was introduced for good reasons and it was known in advance that the success rates would suffer but it was justified on the grounds that the high allocation success rates were achieved by aggressive reclaim. Success rates are expected to suffer even more in 3.6 due to commit [7db8889a: mm: have order > 0 compaction start off where it left] which testing has shown to severely reduce allocation success rates under load - to 0% in one case. There is a proposed change to that patch in this series and it would be ideal if Jim Schutt could retest the workload that led to commit [7db8889a: mm: have order > 0 compaction start off where it left]. This series aims to improve the allocation success rates without regressing the benefits of commit fe2c2a10. The series is based on 3.5 and includes the commit 7db8889a to illustrate what impact it has to success rates. Patch 1 updates a stale comment seeing as I was in the general area. Patch 2 updates reclaim/compaction to reclaim pages scaled on the number of recent failures. Patch 3 captures suitable high-order pages freed by compaction to reduce races with parallel allocation requests. Patch 4 is an upstream commit that has compaction restart free page scanning from an old position instead of always starting from the end of the zone Patch 5 adjusts patch 5 to restores allocation success rates. STRESS-HIGHALLOC 3.5.0-vanilla patches:1-2 patches:1-3 patches:1-5 Pass 1 36.00 ( 0.00%) 61.00 (25.00%) 62.00 (26.00%) 56.00 (20.00%) Pass 2 46.00 ( 0.00%) 61.00 (15.00%) 60.00 (14.00%) 56.00 (10.00%) while Rested 84.00 ( 0.00%) 85.00 ( 1.00%) 86.00 ( 2.00%) 85.00 ( 1.00%) From http://www.csn.ul.ie/~mel/postings/mmtests-20120424/global-dhp__stress-highalloc-performance-ext3/hydra/comparison.html I know that the allocation success rates in 3.3.6 was 78% in comparison to 36% in 3.5. With the full series applied, the success rates are up to around 60% with some variability in the results. This is not as high a success rate but it does not reclaim excessively which is a key point. Previous tests on V1 of this series showed that patch 4 on its own adversely affected high-order allocation success rates. MMTests Statistics: vmstat Page Ins 3037580 3167260 3121588 2939576 Page Outs 8026888 8028472 8026444 8033852 Swap Ins 0 0 0 0 Swap Outs 0 0 0 0 Note that swap in/out rates remain at 0. In 3.3.6 with 78% success rates there were 71881 pages swapped out. Direct pages scanned 97106 59600 118792 84142 Kswapd pages scanned 1231288 1419472 1406569 1406642 Kswapd pages reclaimed 1231221 1419248 1390694 1357820 Direct pages reclaimed 97100 59486 107873 82067 Kswapd efficiency 99% 99% 98% 96% Kswapd velocity 1001.153 1129.622 1082.592 1077.474 Direct efficiency 99% 99% 90% 97% Direct velocity 78.956 47.430 91.431 64.452 kswapd velocity stays at around 1000 pages/second which is reasonable. In kernel 3.3.6, it was 8140 pages/second. include/linux/compaction.h | 4 +- include/linux/mm.h | 1 + include/linux/mmzone.h | 4 ++ mm/compaction.c | 142 +++++++++++++++++++++++++++++++++++++------- mm/internal.h | 7 +++ mm/page_alloc.c | 68 ++++++++++++++++----- mm/vmscan.c | 10 ++++ 7 files changed, 197 insertions(+), 39 deletions(-) -- 1.7.9.2 -- 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>