On Thu, Feb 4, 2021 at 2:49 PM Giovanni Gherdovich <ggherdov...@suse.cz> wrote: > > On Wed, 2021-02-03 at 19:25 +0100, Rafael J. Wysocki wrote: > > [cut] > > > > So below is a prototype of an alternative fix for the issue at hand. > > > > I can't really test it here, because there's no _CPC in the ACPI tables of > > my > > test machines, so testing it would be appreciated. However, AFAICS these > > machines are affected by the performance issue related to the > > scale-invariance > > when they are running acpi-cpufreq, so what we are doing here is not > > entirely > > sufficient. > > > > It looks like the scale-invariance code should ask the cpufreq driver about > > the maximum frequency and note that cpufreq drivers may be changed on the > > fly. > > > > What the patch below does is to add an extra entry to the frequency table > > for > > each CPU to represent the maximum "boost" frequency, so as to cause that > > frequency to be used as cpuinfo.max_freq. > > > > The reason why I think it is better to extend the frequency tables instead > > of simply increasing the frequency for the "P0" entry is because the latter > > may cause "turbo" frequency to be asked for less often. > > > > --- > > drivers/cpufreq/acpi-cpufreq.c | 107 > > ++++++++++++++++++++++++++++++++++++----- > > 1 file changed, 95 insertions(+), 12 deletions(-) > > Hello Rafael, > > thanks for looking at this. Your patch is indeed cleaner than the one I > proposed. > > Preliminary testing is favorable; more tests are running. > > Results from your patch are in the fourth column below; the performance from > v5.10 looks restored. > > I'll follow up once the tests I queued are completed.
Thank you! > TEST : Intel Open Image Denoise, www.openimagedenoise.org > INVOCATION : ./denoise -hdr memorial.pfm -out out.pfm -bench 200 -threads > $NTHREADS > CPU : MODEL : 2x AMD EPYC 7742 > FREQUENCY TABLE : P2: 1.50 GHz > P1: 2.00 GHz > P0: 2.25 GHz > MAX BOOST : 3.40 GHz > > Results: threads, msecs (ratio). Lower is better. > > v5.10 v5.11-rc4 v5.11-rc4-ggherdov v5.11-rc6-rafael > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 1 1069.85 (1.00) 1071.84 (1.00) 1070.42 (1.00) 1069.12 (1.00) > 2 542.24 (1.00) 544.40 (1.00) 544.48 (1.00) 540.81 (1.00) > 4 278.00 (1.00) 278.44 (1.00) 277.72 (1.00) 277.79 (1.00) > 8 149.81 (1.00) 149.61 (1.00) 149.87 (1.00) 149.51 (1.00) > 16 79.01 (1.00) 79.31 (1.00) 78.94 (1.00) 79.02 (1.00) > 24 58.01 (1.00) 58.51 (1.01) 58.15 (1.00) 57.84 (1.00) > 32 46.58 (1.00) 48.30 (1.04) 46.66 (1.00) 46.70 (1.00) > 48 37.29 (1.00) 51.29 (1.38) 37.27 (1.00) 38.10 (1.02) > 64 34.01 (1.00) 49.59 (1.46) 33.71 (0.99) 34.51 (1.01) > 80 31.09 (1.00) 44.27 (1.42) 31.33 (1.01) 31.11 (1.00) > 96 28.56 (1.00) 40.82 (1.43) 28.47 (1.00) 28.65 (1.00) > 112 28.09 (1.00) 40.06 (1.43) 28.63 (1.02) 28.38 (1.01) > 120 28.73 (1.00) 39.78 (1.38) 28.14 (0.98) 28.16 (0.98) > 128 28.93 (1.00) 39.60 (1.37) 29.38 (1.02) 28.55 (0.99)
