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Message-ID: <6df6b42a-6e33-449c-8e57-c07e897142e8@arm.com> Date: Mon, 21 Oct 2024 09:43:42 +0100 From: Christian Loehle <christian.loehle@....com> To: Aboorva Devarajan <aboorvad@...ux.ibm.com>, rafael@...nel.org, daniel.lezcano@...aro.org, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org Cc: gautam@...ux.ibm.com Subject: Re: [PATCH 0/1] cpuidle/menu: Address performance drop from favoring physical over polling cpuidle state Hi Aboorva, On 10/21/24 06:27, Aboorva Devarajan wrote: > [...] > I ran the benchmark again and collected the idle statistics on a different > system since I no longer have access to the previous one. > > Here are the stats I gathered, including data for the menu, teo, and ladder governors: > > Metric | Ladder | Teo | Menu | Menu Patched > -------------------------------------------------------------------------------------------- > Transactions Processed | 42,902,188 | 48,499,709 | 42,653,477 | 48,648,867 > Latency (ms) | 0.313 | 0.277 | 0.315 | 0.276 > TPS | 715,340.96 | 808,672.59 | 711,123.13 | 811,137.40 > -------------------------------------------------------------------------------------------- > Total Usage Difference | 46,680,184 | 66,348,992 | 47,892,509 | 62,366,337 > Usage Diff (CEDE) | 46,680,184 | 7,612,960 | 45,421,436 | 19,237,430 > Usage Diff (Snooze) | 0 | 58,736,032 | 2,471,073 | 43,128,907 > -------------------------------------------------------------------------------------------- > Total Time Difference (s) | 5,552.20 | 5,242.75 | 5,534.62 | 5,238.46 > Time Diff (CEDE) | 5,552.20 | 2,497.89 | 5,431.91 | 3,324.99 > Time Diff (Snooze) | 0.00 | 2,744.86 | 102.71 | 1,913.47 > -------------------------------------------------------------------------------------------- > Total Above Diff | 40,381,398 | 4,520,998 | 38,942,725 | 15,072,345 > Above Diff (CEDE) | 40,381,398 | 4,520,998 | 38,942,725 | 15,072,345 > Above Diff (Snooze) | 0 | 0 | 0 | 0 > -------------------------------------------------------------------------------------------- > Total Below Diff | 0 | 12,362,392 | 405,357 | 8,172,845 > Below Diff (CEDE) | 0 | 0 | 0 | 0 > Below Diff (Snooze) | 0 | 12,362,392 | 405,357 | 8,172,845 > -------------------------------------------------------------------------------------------- > % Above w.r.t. Usage | 86.51% | 6.82% | 81.30% | 24.17% > -------------------------------------------------------------------------------------------- > % Below w.r.t. Usage | 0% | 18.64% | 0.85% | 13.10% > -------------------------------------------------------------------------------------------- > > -------------------------------------------------------------------------------------------- > > Note: > > % Above w.r.t Usage = (Total Above Difference / Total Usage Difference) * 100 > % Below w.r.t Usage = (Total Below Difference / Total Usage Difference) * 100 > > > Menu, Teo, Ladder: This is with menu, teo and ladder governor enabled respectively on v6.12-rc1. > > Menu Patched: This is with menu governor enabled on v6.12-rc + > https://lore.kernel.org/all/20240809073120.250974-2-aboorvad@linux.ibm.com/ > -------------------------------------------------------------------------------------------- > > -------------------------------------------------------------------------------------------- > Inference: > -------------------------------------------------------------------------------------------- > > Transactions Processed: The number of transactions processed in Menu Patched is > 14.06% higher compared to Menu. > > Latency: There is a 12.38% reduction in latency in Menu Patched compared to Menu. > > TPS (Transactions Per Second): The TPS in Menu Patched is 14.06% higher than in > Menu. > -------------------------------------------------------------------------------------------- > > While this patch hasn't completely eliminated the cpuidle miss ratio, but it > has improved see Above w.r.t Usage, Below w.r.t Usage. > > I'll keep investigating why there's still a 24% miss rate in the "above" and > 13% in the "below" stats after the patch. This could be a different issue. > Additionally, I've seen good performance improvements using the teo governor > with the pgbench benchmark, although it didn't provide the same benefit in the > original test. Good to hear and thank you for testing. Indeed the menu idle misses sound somewhat high, given that teo scores fewer. I'd be very curious about the workload where menu patched significantly outperforms teo if you ever come across that again. > [...] > > I ran a similar benchmark using teo cpuidle governor, presented the averaged out > values across 10 runs (has low standard deviation). Below are the results for a > pipe-based wakeup with an approximate 50 microsecond sleep interval: > > > Pipe based wakeup with approx 50 us as sleep interval: > > Metric Ladder Menu Teo Menu Patched > ---------------------------------------------------------------------------------------- > Wakeups 579,690 579,951 578,328 578,363 > Avg wakeup latency (us) 7.456 7.112 4.46067 4.48733 > ======================================================================================== > Sleep interval (us) 51.7333 51.7097 51.8533 51.8477 > ======================================================================================== > State 0 Usage diff 0 7,324 578,361 578,407 > State 0 Time diff (ns) 0 340,115 2.75953e+07 2.75696e+07 > State 0 Above diff 0 0 0 0 > State 0 Below diff 0 0 0.333333 0.666667 > ======================================================================================== > State 1 Usage diff 580,114 572,644 0.666667 9.33333 > State 1 Time diff (ns) 2.74189e+07 2.73901e+07 20.6667 445.333 > State 1 Above diff 579,993 572,535 0.666667 9.33333 > State 1 Below diff 0 0 0 0 > Total Above 579,993 572,535 0.666667 9.33333 > Total Below 0 0 0.333333 0.666667 > ======================================================================================== > Total Above Percent 99.98% 98.7167% 0% 0% --> [1] > Total Below Percent 0% 0% 0% 0% > ======================================================================================== > > Timer based wakeup with approx 50 us as sleep interval: > > Metric Ladder Menu Teo Menu Patched > ---------------------------------------------------------------------------------------- > Sleep interval (us) 53.775 52.3687 52.746 52.327 > ======================================================================================== > State 0 Usage diff 0 572,575 568,419 573,109 > State 0 Time diff (ns) 0 2.84142e+07 2.81956e+07 2.84548e+07 > State 0 Above diff 0 0 0 0 > State 0 Below diff 0 0.333333 1 0.333333 > ======================================================================================== > State 1 Usage diff 558,285 0.333333 0 0 > State 1 Time diff (ns) 2.80965e+07 17 0 0 > State 1 Above diff 558,215 0.333333 0 0 > State 1 Below diff 0 0 0 0 > ======================================================================================== > Total Above 558,215 0.333333 0 0 > Total Below 0 0.333333 1 0.333333 > ======================================================================================== > Total Above Percent 99.99% 0% 0% 0% > Total Below Percent 0% 0% 0% 0% > ======================================================================================== > > > [1] The results does show that the teo governor doesn't have this issue. Glad to see that confirmed, thank you. Regards, Christian
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