Messages in this thread | | | Date | Wed, 21 Feb 2024 12:47:43 -0600 | Subject | Re: [PATCH] [PATCH] amd_pstate: fix erroneous highest_perf value on some CPUs | From | Mario Limonciello <> |
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On 2/21/2024 11:19, Lucas Lee Jing Yi wrote: > On a Ryzen 7840HS the highest_perf value is 196, not 166 as AMD assumed. > This leads to the advertised max clock speed to only be 4.35ghz > instead of 5.14ghz leading to a large degradation in performance. > > Fix the broken assumption and revert back to the old logic for > getting highest_perf. > > TEST: > Geekbench 6 Before Patch: > Single Core: 2325 (-22%)! > Multi Core: 11335 (-10%) > > Geekbench 6 AFTER Patch: > Single Core: 2635 > Multi Core: 12487 >
Yes; the max boost for your system should be 5.1GHz according to the specification [1].
Would you please open a kernel Bugzilla and attach an acpidump and dmesg for your system? I believe we need to better understand your system's situation before deciding on how to correctly approach it.
[1] https://www.amd.com/en/product/13041
> Signed-off-by: Lucas Lee Jing Yi <lucasleeeeeeeee@gmail.com> > --- > drivers/cpufreq/amd-pstate.c | 22 ++++++++++------------ > 1 file changed, 10 insertions(+), 12 deletions(-) > > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c > index 08e112444c27..54df68773620 100644 > --- a/drivers/cpufreq/amd-pstate.c > +++ b/drivers/cpufreq/amd-pstate.c > @@ -50,7 +50,6 @@ > > #define AMD_PSTATE_TRANSITION_LATENCY 20000 > #define AMD_PSTATE_TRANSITION_DELAY 1000 > -#define AMD_PSTATE_PREFCORE_THRESHOLD 166 > > /* > * TODO: We need more time to fine tune processors with shared memory solution > @@ -299,15 +298,12 @@ static int pstate_init_perf(struct amd_cpudata *cpudata) > &cap1); > if (ret) > return ret; > - > - /* For platforms that do not support the preferred core feature, the > - * highest_pef may be configured with 166 or 255, to avoid max frequency > - * calculated wrongly. we take the AMD_CPPC_HIGHEST_PERF(cap1) value as > - * the default max perf. > + > + /* Some CPUs have different highest_perf from others, it is safer > + * to read it than to assume some erroneous value, leading to performance issues. > */ > - if (cpudata->hw_prefcore) > - highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD; > - else > + highest_perf = amd_get_highest_perf(); > + if (highest_perf > AMD_CPPC_HIGHEST_PERF(cap1)) > highest_perf = AMD_CPPC_HIGHEST_PERF(cap1); > > WRITE_ONCE(cpudata->highest_perf, highest_perf); > @@ -329,9 +325,11 @@ static int cppc_init_perf(struct amd_cpudata *cpudata) > if (ret) > return ret; > > - if (cpudata->hw_prefcore) > - highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD; > - else > + /* Some CPUs have different highest_perf from others, it is safer > + * to read it than to assume some erroneous value, leading to performance issues. > + */ > + highest_perf = amd_get_highest_perf(); > + if (highest_perf > cppc_perf.highest_perf) > highest_perf = cppc_perf.highest_perf; > > WRITE_ONCE(cpudata->highest_perf, highest_perf);
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