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author | Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> | 2023-09-07 11:02:07 -0700 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2023-09-11 20:18:17 +0200 |
commit | 37b6ddba967c601479bea418a7ac6ff16b6232b7 (patch) | |
tree | 08fdb8b26e70cb8aa70b01372af04d96d78f675e /drivers/cpufreq/intel_pstate.c | |
parent | 0bb80ecc33a8fb5a682236443c1e740d5c917d1d (diff) | |
download | linux-37b6ddba967c601479bea418a7ac6ff16b6232b7.tar.gz linux-37b6ddba967c601479bea418a7ac6ff16b6232b7.tar.bz2 linux-37b6ddba967c601479bea418a7ac6ff16b6232b7.zip |
cpufreq: intel_pstate: Revise global turbo disable check
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>
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/intel_pstate.c')
-rw-r--r-- | drivers/cpufreq/intel_pstate.c | 6 |
1 files changed, 1 insertions, 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) |