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McKenney" , Matthew Wilcox , Peter Zijlstra , David Hildenbrand , kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Dave Hansen , Andy Lutomirski , Catalin Marinas , David Rientjes , Hugh Dickins , Jann Horn , Lorenzo Stoakes , Mel Gorman , Muchun Song , Peter Xu , Will Deacon , Zach O'Keefe , Dan Carpenter , Frederic Weisbecker , Neeraj Upadhyay References: <20250128113100.GB7145@noisy.programming.kicks-ass.net> <2c599f1f-f63b-4504-a026-46bf73954124@redhat.com> <20250128132847.GB505@noisy.programming.kicks-ass.net> <18172465-37e3-48a9-9d67-0d44fdcb93bd@redhat.com> <8b661116-0a85-4928-91ed-3c01ebbf8d39@bytedance.com> <2212111cad3180948cf388a7e5c8689df0fdda08.camel@surriel.com> <14159fb4-0c59-4653-9265-73f415e70063@bytedance.com> <20250129105920.7a4bffa1@fangorn> <488401565cac6b5f9e3232d0ca481055876c919b.camel@surriel.com> <05da0ae9-073e-4578-b65c-f837c28eead8@paulmck-laptop> <20250129115320.1334ad5f@fangorn> <96f55f36-5cb7-4226-a8ea-374a7891ecff@bytedance.com> <0feb6506a91ea47b306ad50143bde375f462af63.camel@surriel.com> From: Qi Zheng In-Reply-To: <0feb6506a91ea47b306ad50143bde375f462af63.camel@surriel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025/2/1 05:11, Rik van Riel wrote: > On Thu, 2025-01-30 at 01:33 +0800, Qi Zheng wrote: >> >> stress-ng: info:  [671] stressor       bogo ops real time  usr time >> sys >> time   bogo ops/s   bogo ops/s >> stress-ng: info:  [671]                           (secs)    (secs) >> (secs)   (real time) (usr+sys time) >> stress-ng: info:  [671] mmapaddr       19803127     60.01    235.20 >> 1146.76    330007.29     14329.74 > > How stable are these numbers? > > It looks like the bogo ops/s number without the local_bh_disable > was 17233711, while the number is 19803127 after. > > That looks like a 14% speedup. > > This is not back to the 28440843 you had before > MMU_GATHER_RCU_TABLE_FREE was enabled unconditionally, > but it does reduce the size of the regression > considerably, from 40% to 31%. This difference should be caused by the jitter of the test, I just retested it: 1) disable PT_RECLAIM root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [1141] dispatching hogs: 64 mmapaddr stress-ng: info: [1141] successful run completed in 60.09s (1 min, 0.09 secs) stress-ng: info: [1141] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1141] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1141] mmapaddr 32932197 60.01 349.92 1086.26 548798.08 22930.41 stress-ng: info: [1141] for a 60.09s run time: stress-ng: info: [1141] 1442.14s available CPU time stress-ng: info: [1141] 350.29s user time ( 24.29%) stress-ng: info: [1141] 1086.67s system time ( 75.35%) stress-ng: info: [1141] 1436.96s total time ( 99.64%) stress-ng: info: [1141] load average: 41.06 11.81 4.06 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [1270] dispatching hogs: 64 mmapaddr stress-ng: info: [1270] successful run completed in 60.04s (1 min, 0.04 secs) stress-ng: info: [1270] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1270] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1270] mmapaddr 32998610 60.01 346.09 1089.75 549908.86 22982.09 stress-ng: info: [1270] for a 60.04s run time: stress-ng: info: [1270] 1441.08s available CPU time stress-ng: info: [1270] 346.45s user time ( 24.04%) stress-ng: info: [1270] 1090.16s system time ( 75.65%) stress-ng: info: [1270] 1436.61s total time ( 99.69%) stress-ng: info: [1270] load average: 53.09 20.95 7.76 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [1400] dispatching hogs: 64 mmapaddr stress-ng: info: [1400] successful run completed in 60.06s (1 min, 0.06 secs) stress-ng: info: [1400] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1400] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1400] mmapaddr 32880743 60.01 350.36 1084.90 547920.96 22909.26 stress-ng: info: [1400] for a 60.06s run time: stress-ng: info: [1400] 1441.52s available CPU time stress-ng: info: [1400] 350.75s user time ( 24.33%) stress-ng: info: [1400] 1085.29s system time ( 75.29%) stress-ng: info: [1400] 1436.04s total time ( 99.62%) stress-ng: info: [1400] load average: 56.85 28.12 11.16 2) disable PT_RECLAIM + unconditionally enable MMU_GATHER_RCU_TABLE_FREE root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [676] dispatching hogs: 64 mmapaddr stress-ng: info: [676] successful run completed in 60.03s (1 min, 0.03 secs) stress-ng: info: [676] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [676] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [676] mmapaddr 19600836 60.01 206.77 987.29 326626.71 16415.29 stress-ng: info: [676] for a 60.03s run time: stress-ng: info: [676] 1440.76s available CPU time stress-ng: info: [676] 207.08s user time ( 14.37%) stress-ng: info: [676] 987.63s system time ( 68.55%) stress-ng: info: [676] 1194.71s total time ( 82.92%) stress-ng: info: [676] load average: 40.91 11.72 4.03 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [809] dispatching hogs: 64 mmapaddr stress-ng: info: [809] successful run completed in 60.07s (1 min, 0.07 secs) stress-ng: info: [809] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [809] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [809] mmapaddr 19724158 60.02 233.64 1135.94 328625.29 14401.61 stress-ng: info: [809] for a 60.07s run time: stress-ng: info: [809] 1441.78s available CPU time stress-ng: info: [809] 234.00s user time ( 16.23%) stress-ng: info: [809] 1136.38s system time ( 78.82%) stress-ng: info: [809] 1370.38s total time ( 95.05%) stress-ng: info: [809] load average: 55.16 21.29 7.83 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [939] dispatching hogs: 64 mmapaddr stress-ng: info: [939] successful run completed in 60.09s (1 min, 0.09 secs) stress-ng: info: [939] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [939] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [939] mmapaddr 19791766 60.01 238.14 1132.85 329798.06 14436.11 stress-ng: info: [939] for a 60.09s run time: stress-ng: info: [939] 1442.04s available CPU time stress-ng: info: [939] 238.48s user time ( 16.54%) stress-ng: info: [939] 1133.25s system time ( 78.59%) stress-ng: info: [939] 1371.73s total time ( 95.12%) stress-ng: info: [939] load average: 58.39 28.66 11.33 3) disable PT_RECLAIM + unconditionally enable MMU_GATHER_RCU_TABLE_FREE + local_bh_disable root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [702] dispatching hogs: 64 mmapaddr stress-ng: info: [702] successful run completed in 60.05s (1 min, 0.05 secs) stress-ng: info: [702] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [702] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [702] mmapaddr 19838750 60.01 213.89 1038.45 330573.57 15841.35 stress-ng: info: [702] for a 60.05s run time: stress-ng: info: [702] 1441.13s available CPU time stress-ng: info: [702] 214.20s user time ( 14.86%) stress-ng: info: [702] 1038.80s system time ( 72.08%) stress-ng: info: [702] 1253.00s total time ( 86.95%) stress-ng: info: [702] load average: 43.03 12.29 4.22 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [837] dispatching hogs: 64 mmapaddr stress-ng: info: [837] successful run completed in 60.05s (1 min, 0.05 secs) stress-ng: info: [837] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [837] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [837] mmapaddr 19859240 60.01 237.16 1137.80 330931.82 14443.50 stress-ng: info: [837] for a 60.05s run time: stress-ng: info: [837] 1441.15s available CPU time stress-ng: info: [837] 237.54s user time ( 16.48%) stress-ng: info: [837] 1138.20s system time ( 78.98%) stress-ng: info: [837] 1375.74s total time ( 95.46%) stress-ng: info: [837] load average: 44.59 19.18 7.65 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmapaddr 64 stress-ng: info: [974] dispatching hogs: 64 mmapaddr stress-ng: info: [974] successful run completed in 60.07s (1 min, 0.07 secs) stress-ng: info: [974] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [974] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [974] mmapaddr 19769594 60.01 240.35 1141.47 329421.87 14306.92 stress-ng: info: [974] for a 60.07s run time: stress-ng: info: [974] 1441.78s available CPU time stress-ng: info: [974] 240.73s user time ( 16.70%) stress-ng: info: [974] 1141.84s system time ( 79.20%) stress-ng: info: [974] 1382.57s total time ( 95.89%) stress-ng: info: [974] load average: 43.68 22.85 10.43 And I went to look at the source code of stress-ng. For the --mmapaddr option, the prot parameter passed to mmap() is indeed PROT_READ. Therefore, this test will only cause the allocation and freeing of page table pages. For the --mmap option, the prot parameter is PROT_READ | PROT_WRITE, this will also cause the allocation and freeing of normal pages, so I just did the following test: 1) disable PT_RECLAIM root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [668] dispatching hogs: 64 mmap stress-ng: info: [668] successful run completed in 60.07s (1 min, 0.07 secs) stress-ng: info: [668] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [668] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [668] mmap 17568 60.02 434.94 668.32 292.68 15.92 stress-ng: info: [668] for a 60.07s run time: stress-ng: info: [668] 1441.58s available CPU time stress-ng: info: [668] 435.25s user time ( 30.19%) stress-ng: info: [668] 668.77s system time ( 46.39%) stress-ng: info: [668] 1104.02s total time ( 76.58%) stress-ng: info: [668] load average: 40.91 11.74 4.04 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [839] dispatching hogs: 64 mmap stress-ng: info: [839] successful run completed in 60.07s (1 min, 0.07 secs) stress-ng: info: [839] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [839] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [839] mmap 17919 60.01 555.27 853.19 298.60 12.72 stress-ng: info: [839] for a 60.07s run time: stress-ng: info: [839] 1441.66s available CPU time stress-ng: info: [839] 555.63s user time ( 38.54%) stress-ng: info: [839] 853.58s system time ( 59.21%) stress-ng: info: [839] 1409.21s total time ( 97.75%) stress-ng: info: [839] load average: 53.60 21.01 7.77 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [968] dispatching hogs: 64 mmap stress-ng: info: [968] successful run completed in 60.04s (1 min, 0.04 secs) stress-ng: info: [968] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [968] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [968] mmap 17834 60.01 552.80 864.17 297.17 12.59 stress-ng: info: [968] for a 60.04s run time: stress-ng: info: [968] 1440.99s available CPU time stress-ng: info: [968] 553.14s user time ( 38.39%) stress-ng: info: [968] 864.58s system time ( 60.00%) stress-ng: info: [968] 1417.72s total time ( 98.39%) stress-ng: info: [968] load average: 56.07 28.05 11.20 2) disable PT_RECLAIM + unconditionally enable MMU_GATHER_RCU_TABLE_FREE root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [704] dispatching hogs: 64 mmap stress-ng: info: [704] successful run completed in 60.06s (1 min, 0.06 secs) stress-ng: info: [704] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [704] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [704] mmap 17400 60.01 497.26 764.25 289.94 13.79 stress-ng: info: [704] for a 60.06s run time: stress-ng: info: [704] 1441.34s available CPU time stress-ng: info: [704] 497.57s user time ( 34.52%) stress-ng: info: [704] 764.66s system time ( 53.05%) stress-ng: info: [704] 1262.23s total time ( 87.57%) stress-ng: info: [704] load average: 40.69 11.70 4.02 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [875] dispatching hogs: 64 mmap stress-ng: info: [875] successful run completed in 60.05s (1 min, 0.05 secs) stress-ng: info: [875] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [875] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [875] mmap 17874 60.03 562.42 842.09 297.75 12.73 stress-ng: info: [875] for a 60.05s run time: stress-ng: info: [875] 1441.31s available CPU time stress-ng: info: [875] 562.78s user time ( 39.05%) stress-ng: info: [875] 842.50s system time ( 58.45%) stress-ng: info: [875] 1405.28s total time ( 97.50%) stress-ng: info: [875] load average: 51.59 20.56 7.65 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [1004] dispatching hogs: 64 mmap stress-ng: info: [1004] successful run completed in 60.14s (1 min, 0.14 secs) stress-ng: info: [1004] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1004] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1004] mmap 17969 60.01 554.19 849.38 299.42 12.80 stress-ng: info: [1004] for a 60.14s run time: stress-ng: info: [1004] 1443.32s available CPU time stress-ng: info: [1004] 554.59s user time ( 38.42%) stress-ng: info: [1004] 849.81s system time ( 58.88%) stress-ng: info: [1004] 1404.40s total time ( 97.30%) stress-ng: info: [1004] load average: 58.84 28.43 11.22 3) disable PT_RECLAIM + unconditionally enable MMU_GATHER_RCU_TABLE_FREE + local_bh_disable root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [684] dispatching hogs: 64 mmap stress-ng: info: [684] successful run completed in 60.05s (1 min, 0.05 secs) stress-ng: info: [684] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [684] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [684] mmap 17817 60.01 555.70 847.53 296.88 12.70 stress-ng: info: [684] for a 60.05s run time: stress-ng: info: [684] 1441.12s available CPU time stress-ng: info: [684] 556.10s user time ( 38.59%) stress-ng: info: [684] 847.94s system time ( 58.84%) stress-ng: info: [684] 1404.04s total time ( 97.43%) stress-ng: info: [684] load average: 41.27 11.82 4.06 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [815] dispatching hogs: 64 mmap stress-ng: info: [815] successful run completed in 60.06s (1 min, 0.06 secs) stress-ng: info: [815] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [815] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [815] mmap 17860 60.01 553.77 856.56 297.60 12.66 stress-ng: info: [815] for a 60.06s run time: stress-ng: info: [815] 1441.44s available CPU time stress-ng: info: [815] 554.13s user time ( 38.44%) stress-ng: info: [815] 856.94s system time ( 59.45%) stress-ng: info: [815] 1411.07s total time ( 97.89%) stress-ng: info: [815] load average: 49.71 20.32 7.66 root@debian:~# stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --mmap 64 stress-ng: info: [944] dispatching hogs: 64 mmap stress-ng: info: [944] successful run completed in 60.08s (1 min, 0.08 secs) stress-ng: info: [944] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [944] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [944] mmap 17932 60.01 556.23 857.77 298.82 12.68 stress-ng: info: [944] for a 60.08s run time: stress-ng: info: [944] 1442.01s available CPU time stress-ng: info: [944] 556.63s user time ( 38.60%) stress-ng: info: [944] 858.16s system time ( 59.51%) stress-ng: info: [944] 1414.79s total time ( 98.11%) stress-ng: info: [944] load average: 56.02 27.74 11.12 It looks like there is basically no difference in bogo ops/s. Thanks! >