Messages in this thread | | | Date | Thu, 24 Nov 2022 11:50:13 +0800 | Subject | Re: [PATCH v6 0/4] sched/fair: Improve scan efficiency of SIS | From | Abel Wu <> |
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Hi Prateek, thanks again for your detailed test!
On 11/22/22 7:28 PM, K Prateek Nayak wrote: > Hello Abel, > > Following are the results for hackbench with larger number of > groups, ycsb-mongodb, Spec-JBB, and unixbench. Apart for > a regression in unixbench spawn in NPS2 and NPS4 mode and > unixbench syscall in NPs2 mode, everything looks good. > > ... > > -> unixbench-syscall > > o NPS4 > > kernel: tip sis_core > Min unixbench-syscall-1 2971799.80 ( 0.00%) 2979335.60 ( -0.25%) > Min unixbench-syscall-512 7824196.90 ( 0.00%) 8155610.20 ( -4.24%) > Amean unixbench-syscall-1 2973045.43 ( 0.00%) 2982036.13 * -0.30%* > Amean unixbench-syscall-512 7826302.17 ( 0.00%) 8173026.57 * -4.43%* <-- Regression in syscall for larger worker count > CoeffVar unixbench-syscall-1 0.04 ( 0.00%) 0.09 (-139.63%) > CoeffVar unixbench-syscall-512 0.03 ( 0.00%) 0.20 (-701.13%) > > > -> unixbench-spawn > > o NPS1 > > kernel: tip sis_core > Min unixbench-spawn-1 6536.50 ( 0.00%) 6000.30 ( -8.20%) > Min unixbench-spawn-512 72571.40 ( 0.00%) 70829.60 ( -2.40%) > Hmean unixbench-spawn-1 6811.16 ( 0.00%) 7016.11 ( 3.01%) > Hmean unixbench-spawn-512 72801.77 ( 0.00%) 71012.03 * -2.46%* > CoeffVar unixbench-spawn-1 3.69 ( 0.00%) 13.52 (-266.69%) > CoeffVar unixbench-spawn-512 0.27 ( 0.00%) 0.22 ( 18.25%) > > o NPS2 > > kernel: tip sis_core > Min unixbench-spawn-1 7042.20 ( 0.00%) 7078.70 ( 0.52%) > Min unixbench-spawn-512 85571.60 ( 0.00%) 77362.60 ( -9.59%) > Hmean unixbench-spawn-1 7199.01 ( 0.00%) 7276.55 ( 1.08%) > Hmean unixbench-spawn-512 85717.77 ( 0.00%) 77923.73 * -9.09%* <-- Regression in spawn test for larger worker count > CoeffVar unixbench-spawn-1 3.50 ( 0.00%) 3.30 ( 5.70%) > CoeffVar unixbench-spawn-512 0.20 ( 0.00%) 0.82 (-304.88%) > > o NPS4 > > kernel: tip sis_core > Min unixbench-spawn-1 7521.90 ( 0.00%) 8102.80 ( 7.72%) > Min unixbench-spawn-512 84245.70 ( 0.00%) 73074.50 ( -13.26%) > Hmean unixbench-spawn-1 7659.12 ( 0.00%) 8645.19 * 12.87%* > Hmean unixbench-spawn-512 84908.77 ( 0.00%) 73409.49 * -13.54%* <-- Regression in spawn test for larger worker count > CoeffVar unixbench-spawn-1 1.92 ( 0.00%) 5.78 (-200.56%) > CoeffVar unixbench-spawn-512 0.76 ( 0.00%) 0.41 ( 46.58%) > > ... > > For unixbench regressions, I do not see anything obvious jump up > in perf traces captureed with IBS. top shows over 99% utilization > which would ideally mean there are not many updates to the mask. > I'll take some more look at the spawn test case and get back to you.
These regressions seems to be common in full parallel tests. I guess it might be due to over updating the idle cpumask when LLC is overloaded which is not necessary if SIS_UTIL enabled, but I need to dig it further. Maybe the rq avg_idle or nr_idle_scan need to be taken into consideration as well. Thanks for providing these important information.
> > ~~~~~~~~~~~~~ > ~ Hackbench ~ > ~~~~~~~~~~~~~ > > $ perf bench sched messaging -p -l 50000 -g <groups> > > o NPS1 > > kernel: tip sis_core > 32-groups: 6.20 (0.00 pct) 5.86 (5.48 pct) > 64-groups: 16.55 (0.00 pct) 15.21 (8.09 pct) > 128-groups: 42.57 (0.00 pct) 34.63 (18.65 pct) > 256-groups: 71.69 (0.00 pct) 67.11 (6.38 pct) > 512-groups: 108.48 (0.00 pct) 110.23 (-1.61 pct) > > o NPS2 > > kernel: tip sis_core > 32-groups: 6.56 (0.00 pct) 5.60 (14.63 pct) > 64-groups: 15.74 (0.00 pct) 14.45 (8.19 pct) > 128-groups: 39.93 (0.00 pct) 35.33 (11.52 pct) > 256-groups: 74.49 (0.00 pct) 69.65 (6.49 pct) > 512-groups: 112.22 (0.00 pct) 113.75 (-1.36 pct) > > o NPS4: > > kernel: tip sis_core > 32-groups: 9.48 (0.00 pct) 5.64 (40.50 pct) > 64-groups: 15.38 (0.00 pct) 14.13 (8.12 pct) > 128-groups: 39.93 (0.00 pct) 34.47 (13.67 pct) > 256-groups: 75.31 (0.00 pct) 67.98 (9.73 pct) > 512-groups: 115.37 (0.00 pct) 111.15 (3.65 pct) > > Note: Hackbench with 32-groups show run to run variation > on tip but is more stable with sis_core. Hackbench for > 64-groups and beyond is stable on both kernels. > The result is consistent with mine except 512-groups which I didn't test. The 512-groups test may have the same problem aforementioned.
Thanks & Regards, Abel
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