Re: [RFC PATCH 0/5] compaction: changing initial position of scanners
From: Vlastimil Babka
Date: Tue Jan 20 2015 - 04:02:26 EST
On 01/19/2015 11:05 AM, Vlastimil Babka wrote:
> Preliminary testing with THP-like allocations has shown similar improvements,
> which is somewhat surprising, because THP allocations do not use sync
> and thus do not defer compaction; but changing the pivot is currently tied
> to restarting from deferred compaction. Possibly this is due to the other
> allocation activity than the stress-highalloc test itself. I will post these
> results when full measurements are done.
So here are the full results, before patch 5:
3.19-rc4 3.19-rc4 3.19-rc4
4-thp-1 4-thp-2 4-thp-3
Success 1 Min 24.00 ( 0.00%) 14.00 ( 41.67%) 16.00 ( 33.33%)
Success 1 Mean 29.80 ( 0.00%) 17.00 ( 42.95%) 19.80 ( 33.56%)
Success 1 Max 33.00 ( 0.00%) 25.00 ( 24.24%) 29.00 ( 12.12%)
Success 2 Min 26.00 ( 0.00%) 15.00 ( 42.31%) 17.00 ( 34.62%)
Success 2 Mean 32.60 ( 0.00%) 19.20 ( 41.10%) 21.20 ( 34.97%)
Success 2 Max 37.00 ( 0.00%) 28.00 ( 24.32%) 30.00 ( 18.92%)
Success 3 Min 85.00 ( 0.00%) 82.00 ( 3.53%) 80.00 ( 5.88%)
Success 3 Mean 86.20 ( 0.00%) 83.20 ( 3.48%) 81.20 ( 5.80%)
Success 3 Max 87.00 ( 0.00%) 84.00 ( 3.45%) 82.00 ( 5.75%)
3.19-rc4 3.19-rc4 3.19-rc4
4-thp-1 4-thp-2 4-thp-3
User 6798.70 6905.43 6941.09
System 1064.04 1062.94 1062.76
Elapsed 2108.98 2026.84 2039.40
3.19-rc4 3.19-rc4 3.19-rc4
4-thp-1 4-thp-2 4-thp-3
Minor Faults 198099852 197531505 197503750
Major Faults 483 422 490
Swap Ins 86 55 113
Swap Outs 3138 887 399
Allocation stalls 6523 4619 4816
DMA allocs 20 21 29
DMA32 allocs 124645618 123937328 123927500
Normal allocs 58904757 58753982 58818313
Movable allocs 0 0 0
Direct pages scanned 428919 361735 402238
Kswapd pages scanned 2110062 2070576 2042000
Kswapd pages reclaimed 2104207 2067640 2026147
Direct pages reclaimed 427965 361045 401398
Kswapd efficiency 99% 99% 99%
Kswapd velocity 1019.443 1032.145 1015.507
Direct efficiency 99% 99% 99%
Direct velocity 207.225 180.319 200.037
Percentage direct scans 16% 14% 16%
Zone normal velocity 408.313 391.138 385.933
Zone dma32 velocity 818.355 821.320 829.605
Zone dma velocity 0.000 0.006 0.006
Page writes by reclaim 3352.000 963.000 517.000
Page writes file 213 75 117
Page writes anon 3138 887 399
Page reclaim immediate 1144 1066 14181
Sector Reads 4628816 4522758 4532221
Sector Writes 12767080 12671744 12651826
Page rescued immediate 0 0 0
Slabs scanned 1697125 1504150 1497662
Direct inode steals 18505 12670 12166
Kswapd inode steals 34595 31472 30069
Kswapd skipped wait 0 0 0
THP fault alloc 239 220 235
THP collapse alloc 507 406 478
THP splits 14 13 12
THP fault fallback 28 25 6
THP collapse fail 16 21 19
Compaction stalls 2661 1953 2062
Compaction success 1005 738 832
Compaction failures 1656 1215 1229
Page migrate success 2137343 1941288 1984697
Page migrate failure 9345 5923 7109
Compaction pages isolated 4630988 4169422 4271015
Compaction migrate scanned 42109445 35090957 37926766
Compaction free scanned 150533970 131933800 126682354
Compaction cost 2601 2339 2406
After patch 5:
3.19-rc4 3.19-rc4 3.19-rc4
5-thp-1 5-thp-2 5-thp-3
Success 1 Min 43.00 ( 0.00%) 35.00 ( 18.60%) 33.00 ( 23.26%)
Success 1 Mean 44.80 ( 0.00%) 37.20 ( 16.96%) 36.40 ( 18.75%)
Success 1 Max 46.00 ( 0.00%) 38.00 ( 17.39%) 41.00 ( 10.87%)
Success 2 Min 53.00 ( 0.00%) 44.00 ( 16.98%) 40.00 ( 24.53%)
Success 2 Mean 55.60 ( 0.00%) 47.60 ( 14.39%) 43.60 ( 21.58%)
Success 2 Max 58.00 ( 0.00%) 50.00 ( 13.79%) 46.00 ( 20.69%)
Success 3 Min 85.00 ( 0.00%) 81.00 ( 4.71%) 79.00 ( 7.06%)
Success 3 Mean 86.40 ( 0.00%) 83.40 ( 3.47%) 80.20 ( 7.18%)
Success 3 Max 88.00 ( 0.00%) 85.00 ( 3.41%) 82.00 ( 6.82%)
3.19-rc4 3.19-rc4 3.19-rc4
5-thp-1 5-thp-2 5-thp-3
User 6690.38 6734.92 6772.31
System 1065.54 1063.26 1064.48
Elapsed 2172.84 2153.99 2162.77
3.19-rc4 3.19-rc4 3.19-rc4
5-thp-1 5-thp-2 5-thp-3
Minor Faults 196642124 197072025 196458816
Major Faults 712 629 663
Swap Ins 112 89 119
Swap Outs 2425 1615 955
Allocation stalls 10987 8689 8072
DMA allocs 13 13 12
DMA32 allocs 124048790 124176073 123636557
Normal allocs 58641381 58758990 58548760
Movable allocs 0 0 0
Direct pages scanned 607943 519167 491800
Kswapd pages scanned 2091239 2093530 2080230
Kswapd pages reclaimed 2085935 2090069 2076784
Direct pages reclaimed 607103 518178 490870
Kswapd efficiency 99% 99% 99%
Kswapd velocity 953.698 980.452 978.692
Direct efficiency 99% 99% 99%
Direct velocity 277.249 243.139 231.379
Percentage direct scans 22% 19% 19%
Zone normal velocity 411.137 400.519 393.191
Zone dma32 velocity 819.809 823.068 816.877
Zone dma velocity 0.000 0.004 0.004
Page writes by reclaim 2568.800 1735.400 1112.200
Page writes file 143 120 156
Page writes anon 2425 1615 955
Page reclaim immediate 1316 1240 1460
Sector Reads 4801026 4810421 4766392
Sector Writes 12521168 12599312 12490746
Page rescued immediate 0 0 0
Slabs scanned 1998998 1873533 1826614
Direct inode steals 39894 44540 29447
Kswapd inode steals 34313 24112 32393
Kswapd skipped wait 0 0 0
THP fault alloc 204 227 190
THP collapse alloc 554 555 463
THP splits 14 16 11
THP fault fallback 3 3 0
THP collapse fail 15 16 20
Compaction stalls 3742 3350 3257
Compaction success 1427 1298 1262
Compaction failures 2315 2051 1995
Page migrate success 2557969 2615986 2766293
Page migrate failure 11532 7297 8779
Compaction pages isolated 5601557 5698249 6044777
Compaction migrate scanned 16776380 20331554 22910553
Compaction free scanned 213184847 172781034 169740956
Compaction cost 2879 2966 3146
Success rates are still worse on second iteration compared to first, but much better overal.
Let's repeat compaction stats before patch 5, for easier comparison:
Compaction stalls 2661 1953 2062
Compaction success 1005 738 832
Compaction failures 1656 1215 1229
Page migrate success 2137343 1941288 1984697
Page migrate failure 9345 5923 7109
Compaction pages isolated 4630988 4169422 4271015
Compaction migrate scanned 42109445 35090957 37926766
Compaction free scanned 150533970 131933800 126682354
Compaction cost 2601 2339 2406
Again, migrate scanned went actually down after patch 5, the rest went up as
compaction was more successful and less deferred.
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