On Thu, 2021-02-04 at 18:25 +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <[email protected]> > > A severe performance regression on AMD EPYC processors when using > the schedutil scaling governor was discovered by Phoronix.com and > attributed to the following commits: > > 41ea667227ba ("x86, sched: Calculate frequency invariance for > AMD systems") > > 976df7e5730e ("x86, sched: Use midpoint of max_boost and max_P > for frequency invariance on AMD EPYC") > > [snip] > > Fixes: 41ea667227ba ("x86, sched: Calculate frequency invariance for AMD > systems") > Fixes: 976df7e5730e ("x86, sched: Use midpoint of max_boost and max_P for > frequency invariance on AMD EPYC") > Fixes: db865272d9c4 ("cpufreq: Avoid configuring old governors as default > with intel_pstate") > Link: > https://www.phoronix.com/scan.php?page=article&item=linux511-amd-schedutil&num=1 > Link: > https://lore.kernel.org/linux-pm/[email protected]/ > Reported-by: Michael Larabel <[email protected]> > Diagnosed-by: Giovanni Gherdovich <[email protected]> > Signed-off-by: Rafael J. Wysocki <[email protected]> > --- > drivers/cpufreq/acpi-cpufreq.c | 107 > ++++++++++++++++++++++++++++++++++++----- > 1 file changed, 95 insertions(+), 12 deletions(-) > > Index: linux-pm/drivers/cpufreq/acpi-cpufreq.c > =================================================================== > --- linux-pm.orig/drivers/cpufreq/acpi-cpufreq.c > +++ linux-pm/drivers/cpufreq/acpi-cpufreq.c > [...]
Tested-by: Giovanni Gherdovich <[email protected]> Reviewed-by: Giovanni Gherdovich <[email protected]> Note there is also the Tested-by: Michael, from the other thread https://lore.kernel.org/lkml/[email protected]/ I tested this patch with the "NASA Parallel Benchmarks" from [link below], the results confirms that the 5.10 performance is recovered: Ratios of completion times, lower is better (5.10 is the baseline) 5.10 5.11-rc6 5.11-rc6-ggherdov 5.11-rc6-rafael ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Integer Sort 1.00 1.21 0.91 0.93 Embarrassingly Parallel 1.00 1.60 1.00 1.00 Discrete FFT 1.00 1.68 0.67 0.67 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 [link] https://www.nas.nasa.gov/publications/npb.html Thanks, Giovanni
