Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932767AbaLDRN6 (ORCPT ); Thu, 4 Dec 2014 12:13:58 -0500 Received: from cantor2.suse.de ([195.135.220.15]:58010 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932464AbaLDRNR (ORCPT ); Thu, 4 Dec 2014 12:13:17 -0500 From: Vlastimil Babka To: linux-mm@kvack.org, Joonsoo Kim Cc: linux-kernel@vger.kernel.org, Minchan Kim , Mel Gorman , Rik van Riel , David Rientjes , Vlastimil Babka Subject: [PATCH 0/3] page stealing tweaks Date: Thu, 4 Dec 2014 18:12:55 +0100 Message-Id: <1417713178-10256-1-git-send-email-vbabka@suse.cz> X-Mailer: git-send-email 2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When studying page stealing, I noticed some weird looking decisions in try_to_steal_freepages(). The first I assume is a bug (Patch 1), the following two patches were driven by evaluation. Testing was done with stress-highalloc of mmtests, using the mm_page_alloc_extfrag tracepoint and postprocessing to get counts of how often page stealing occurs for individual migratetypes, and what migratetypes are used for fallbacks. Arguably, the worst case of page stealing is when UNMOVABLE allocation steals from MOVABLE pageblock. RECLAIMABLE allocation stealing from MOVABLE allocation is also not ideal, so the goal is to minimize these two cases. For some reason, the first patch increased the number of page stealing events for MOVABLE allocations, and I am still not sure why. In theory these events are not as bad, and the third patch does more than just to correct this. Here are the results, baseline (column 26) is 3.17-rc7 with compaction patches from -mm. First, the results with benchmark set to mimic non-THP-like whole-pageblock allocations. Discussion below: stress-highalloc 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-nothp 27-nothp 28-nothp 29-nothp Success 1 Min 20.00 ( 0.00%) 31.00 (-55.00%) 33.00 (-65.00%) 23.00 (-15.00%) Success 1 Mean 32.70 ( 0.00%) 39.00 (-19.27%) 39.10 (-19.57%) 35.80 ( -9.48%) Success 1 Max 42.00 ( 0.00%) 44.00 ( -4.76%) 46.00 ( -9.52%) 45.00 ( -7.14%) Success 2 Min 20.00 ( 0.00%) 33.00 (-65.00%) 36.00 (-80.00%) 24.00 (-20.00%) Success 2 Mean 33.90 ( 0.00%) 41.30 (-21.83%) 41.70 (-23.01%) 36.80 ( -8.55%) Success 2 Max 44.00 ( 0.00%) 49.00 (-11.36%) 49.00 (-11.36%) 45.00 ( -2.27%) Success 3 Min 84.00 ( 0.00%) 86.00 ( -2.38%) 86.00 ( -2.38%) 85.00 ( -1.19%) Success 3 Mean 86.40 ( 0.00%) 87.20 ( -0.93%) 87.20 ( -0.93%) 86.80 ( -0.46%) Success 3 Max 88.00 ( 0.00%) 89.00 ( -1.14%) 89.00 ( -1.14%) 88.00 ( 0.00%) 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-nothp 27-nothp 28-nothp 29-nothp User 6818.93 6775.23 6759.60 6783.81 System 1055.97 1056.31 1055.37 1057.36 Elapsed 2150.18 2211.63 2196.91 2201.93 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-nothp 27-nothp 28-nothp 29-nothp Minor Faults 198162003 197936707 197750617 198414323 Major Faults 462 511 533 490 Swap Ins 29 31 42 21 Swap Outs 2142 2225 2616 2276 Allocation stalls 6030 7716 6856 6175 DMA allocs 112 102 128 73 DMA32 allocs 124578777 124503016 124372538 124840569 Normal allocs 59157970 59165895 59160083 59154005 Movable allocs 0 0 0 0 Direct pages scanned 353190 424846 395619 359421 Kswapd pages scanned 2201775 2221571 2223699 2254336 Kswapd pages reclaimed 2196630 2216042 2218175 2242737 Direct pages reclaimed 352402 423989 394801 358321 Kswapd efficiency 99% 99% 99% 99% Kswapd velocity 1011.483 1019.369 1016.418 1010.895 Direct efficiency 99% 99% 99% 99% Direct velocity 162.253 194.941 180.832 161.173 Percentage direct scans 13% 16% 15% 13% Zone normal velocity 381.505 402.030 393.093 376.382 Zone dma32 velocity 792.218 812.269 804.143 795.679 Zone dma velocity 0.012 0.011 0.014 0.007 Page writes by reclaim 2316.900 2366.600 2791.300 2492.700 Page writes file 174 141 174 216 Page writes anon 2142 2225 2616 2276 Page reclaim immediate 1381 1586 1314 8126 Sector Reads 4703932 4775640 4750501 4747452 Sector Writes 12758092 12720075 12695676 12790100 Page rescued immediate 0 0 0 0 Slabs scanned 1750170 1871811 1847197 1822608 Direct inode steals 14468 14838 14872 14241 Kswapd inode steals 38766 40510 40353 40442 Kswapd skipped wait 0 0 0 0 THP fault alloc 262 221 239 239 THP collapse alloc 506 494 535 491 THP splits 14 12 14 14 THP fault fallback 7 33 10 39 THP collapse fail 17 18 16 18 Compaction stalls 2746 3359 3185 2981 Compaction success 1025 1188 1153 1097 Compaction failures 1721 2170 2032 1884 Page migrate success 3889927 4512417 4340044 4128768 Page migrate failure 14551 17660 17096 14686 Compaction pages isolated 8058458 9337143 8974871 8554984 Compaction migrate scanned 156216179 187390755 178241572 163503245 Compaction free scanned 317797413 388387641 361523988 341521402 Compaction cost 5284 6173 5923 5592 NUMA alloc hit 181314344 181142494 180975258 181531369 NUMA alloc miss 0 0 0 0 NUMA interleave hit 0 0 0 0 NUMA alloc local 181314344 181142494 180975258 181531369 NUMA base PTE updates 0 0 0 0 NUMA huge PMD updates 0 0 0 0 NUMA page range updates 0 0 0 0 NUMA hint faults 0 0 0 0 NUMA hint local faults 0 0 0 0 NUMA hint local percent 100 100 100 100 NUMA pages migrated 0 0 0 0 AutoNUMA cost 0% 0% 0% 0% 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-nothp 27-nothp 28-nothp 29-nothp Page alloc extfrag event 7223461 10651213 10274135 3785074 Extfrag fragmenting 7221775 10648719 10272431 3782605 Extfrag fragmenting for unmovable 20264 16784 2668 2768 Extfrag fragmenting unmovable stealing from movable 10814 7531 2231 2091 Extfrag fragmenting for reclaimable 1937 1114 1138 1268 Extfrag fragmenting reclaimable stealing from movable 1731 882 914 973 Extfrag fragmenting for movable 7199574 10630821 10268625 3778569 As can be seen, success rates are not very much affected, or perhaps the first patch improves them slightly. But the reduction of extfrag events is quite prominent, especially for unmovable allocations polluting (potentially permanently) movable pageblocks. For completeness, the results with benchark set to mimic THP allocations are below. It's not so different, so no extra discussion. stress-highalloc 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-thp 27-thp 28-thp 29-thp Success 1 Min 20.00 ( 0.00%) 27.00 (-35.00%) 26.00 (-30.00%) 22.00 (-10.00%) Success 1 Mean 28.90 ( 0.00%) 33.00 (-14.19%) 31.90 (-10.38%) 29.60 ( -2.42%) Success 1 Max 36.00 ( 0.00%) 40.00 (-11.11%) 39.00 ( -8.33%) 35.00 ( 2.78%) Success 2 Min 20.00 ( 0.00%) 28.00 (-40.00%) 30.00 (-50.00%) 23.00 (-15.00%) Success 2 Mean 31.20 ( 0.00%) 36.70 (-17.63%) 35.20 (-12.82%) 32.50 ( -4.17%) Success 2 Max 39.00 ( 0.00%) 43.00 (-10.26%) 42.00 ( -7.69%) 43.00 (-10.26%) Success 3 Min 85.00 ( 0.00%) 86.00 ( -1.18%) 87.00 ( -2.35%) 86.00 ( -1.18%) Success 3 Mean 86.90 ( 0.00%) 87.30 ( -0.46%) 87.70 ( -0.92%) 87.20 ( -0.35%) Success 3 Max 88.00 ( 0.00%) 88.00 ( 0.00%) 90.00 ( -2.27%) 89.00 ( -1.14%) 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-thp 27-thp 28-thp 29-thp User 6819.54 6791.98 6817.78 6780.39 System 1060.01 1061.72 1059.55 1060.22 Elapsed 2143.61 2169.23 2151.94 2164.37 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-thp 27-thp 28-thp 29-thp Minor Faults 197991650 197731531 197676212 198108344 Major Faults 467 517 485 463 Swap Ins 55 42 55 37 Swap Outs 2743 2628 2848 2423 Allocation stalls 5674 6859 5830 5430 DMA allocs 21 19 18 20 DMA32 allocs 124822788 124717762 124599426 124998427 Normal allocs 58689613 58661322 58715465 58613337 Movable allocs 0 0 0 0 Direct pages scanned 425873 497589 437964 440959 Kswapd pages scanned 2106472 2092938 2123314 2137886 Kswapd pages reclaimed 2100750 2087313 2117523 2124031 Direct pages reclaimed 424875 496616 437006 439572 Kswapd efficiency 99% 99% 99% 99% Kswapd velocity 986.439 999.617 1016.928 984.321 Direct efficiency 99% 99% 99% 99% Direct velocity 199.432 237.656 209.756 203.025 Percentage direct scans 16% 19% 17% 17% Zone normal velocity 396.728 411.978 412.730 391.261 Zone dma32 velocity 789.143 825.294 813.954 796.086 Zone dma velocity 0.000 0.000 0.000 0.000 Page writes by reclaim 2963.000 2735.600 2981.900 2640.500 Page writes file 219 107 133 217 Page writes anon 2743 2628 2848 2423 Page reclaim immediate 1504 1609 1622 9672 Sector Reads 4638068 4700778 4687436 4690935 Sector Writes 12744701 12689336 12685726 12742547 Page rescued immediate 0 0 0 0 Slabs scanned 1612929 1704964 1659159 1670590 Direct inode steals 15564 17989 16063 17179 Kswapd inode steals 31322 31013 31563 31266 Kswapd skipped wait 0 0 0 0 THP fault alloc 250 227 246 223 THP collapse alloc 517 515 504 487 THP splits 15 13 14 11 THP fault fallback 10 24 5 38 THP collapse fail 17 18 16 18 Compaction stalls 2482 2794 2687 2608 Compaction success 894 1016 995 972 Compaction failures 1588 1778 1692 1636 Page migrate success 2306759 2283240 2298373 2228802 Page migrate failure 10645 12648 10681 10023 Compaction pages isolated 4906442 4878707 4907827 4768580 Compaction migrate scanned 40396525 46362656 44372629 42315303 Compaction free scanned 134008519 146858466 131814222 132434783 Compaction cost 2770 2787 2789 2700 NUMA alloc hit 181150856 180941682 180895401 181254771 NUMA alloc miss 0 0 0 0 NUMA interleave hit 0 0 0 0 NUMA alloc local 181150856 180941682 180895401 181254771 NUMA base PTE updates 0 0 0 0 NUMA huge PMD updates 0 0 0 0 NUMA page range updates 0 0 0 0 NUMA hint faults 0 0 0 0 NUMA hint local faults 0 0 0 0 NUMA hint local percent 100 100 100 100 NUMA pages migrated 0 0 0 0 AutoNUMA cost 0% 0% 0% 0% 3.17-rc7 3.17-rc7 3.17-rc7 3.17-rc7 26-thp 27-thp 28-thp 29-thp Page alloc extfrag event 4270316 5661910 5018754 2062787 Extfrag fragmenting 4268643 5660158 5016977 2061077 Extfrag fragmenting for unmovable 21632 17627 1985 1984 Extfrag fragmenting unmovable placed with movable 12428 9011 1663 1506 Extfrag fragmenting for reclaimable 1682 1106 1290 1401 Extfrag fragmenting reclaimable placed with movable 1480 917 1072 1132 Extfrag fragmenting for movable 4245329 5641425 5013702 2057692 Vlastimil Babka (3): mm: when stealing freepages, also take pages created by splitting buddy page mm: more aggressive page stealing for UNMOVABLE allocations mm: always steal split buddies in fallback allocations mm/page_alloc.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/