| Message ID | 20230907180207.3274207-1-srinivas.pandruvada@linux.intel.com (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | cpufreq: intel_pstate: Fix global turbo disable check | expand |
On Thu, Sep 7, 2023 at 8:02 PM Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote: > > Setting global turbo flag based on CPU 0 P-state limits is problematic > as it limits max P-state request on every CPU on the system just based > on its P-state limits. > > There are two cases in which global.turbo_disabled flag is set: > - When the MSR_IA32_MISC_ENABLE_TURBO_DISABLE bit is set to 1 > in the MSR MSR_IA32_MISC_ENABLE. This bit can be only changed by > the system BIOS before power up. > - When the max non turbo P-state is same as max turbo P-state for CPU 0. > > The second check is not a valid to decide global turbo state based on > the CPU 0. CPU 0 max turbo P-state can be same as max non turbo P-state, > but for other CPUs this may not be true. > > There is no guarantee that max P-state limits are same for every CPU. This > is possible that during fusing max P-state for a CPU is constrained. Also > with the Intel Speed Select performance profile, CPU 0 may not be present > in all profiles. In this case the max non turbo and turbo P-state can be > set to the lowest possible P-state by the hardware when switched to > such profile. Since max non turbo and turbo P-state is same, > global.turbo_disabled flag will be set. > > Once global.turbo_disabled is set, any scaling max and min frequency > update for any CPU will result in its max P-state constrained to the max > non turbo P-state. > > Hence remove the check of max non turbo P-state equal to max turbo P-state > of CPU 0 to set global turbo disabled flag. > > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> > --- > drivers/cpufreq/intel_pstate.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index dc50c9fb488d..a534a1f7f1ee 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -571,13 +571,9 @@ static void intel_pstate_hybrid_hwp_adjust(struct cpudata *cpu) > static inline void update_turbo_state(void) > { > u64 misc_en; > - struct cpudata *cpu; > > - cpu = all_cpu_data[0]; > rdmsrl(MSR_IA32_MISC_ENABLE, misc_en); > - global.turbo_disabled = > - (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE || > - cpu->pstate.max_pstate == cpu->pstate.turbo_pstate); > + global.turbo_disabled = misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE; > } > > static int min_perf_pct_min(void) > -- Applied as 6.7 material (under a slightly modified subject), thanks!
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index dc50c9fb488d..a534a1f7f1ee 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -571,13 +571,9 @@ static void intel_pstate_hybrid_hwp_adjust(struct cpudata *cpu) static inline void update_turbo_state(void) { u64 misc_en; - struct cpudata *cpu; - cpu = all_cpu_data[0]; rdmsrl(MSR_IA32_MISC_ENABLE, misc_en); - global.turbo_disabled = - (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE || - cpu->pstate.max_pstate == cpu->pstate.turbo_pstate); + global.turbo_disabled = misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE; } static int min_perf_pct_min(void)
Setting global turbo flag based on CPU 0 P-state limits is problematic as it limits max P-state request on every CPU on the system just based on its P-state limits. There are two cases in which global.turbo_disabled flag is set: - When the MSR_IA32_MISC_ENABLE_TURBO_DISABLE bit is set to 1 in the MSR MSR_IA32_MISC_ENABLE. This bit can be only changed by the system BIOS before power up. - When the max non turbo P-state is same as max turbo P-state for CPU 0. The second check is not a valid to decide global turbo state based on the CPU 0. CPU 0 max turbo P-state can be same as max non turbo P-state, but for other CPUs this may not be true. There is no guarantee that max P-state limits are same for every CPU. This is possible that during fusing max P-state for a CPU is constrained. Also with the Intel Speed Select performance profile, CPU 0 may not be present in all profiles. In this case the max non turbo and turbo P-state can be set to the lowest possible P-state by the hardware when switched to such profile. Since max non turbo and turbo P-state is same, global.turbo_disabled flag will be set. Once global.turbo_disabled is set, any scaling max and min frequency update for any CPU will result in its max P-state constrained to the max non turbo P-state. Hence remove the check of max non turbo P-state equal to max turbo P-state of CPU 0 to set global turbo disabled flag. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> --- drivers/cpufreq/intel_pstate.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)