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| author | Stratos Karafotis <stratosk@semaphore.gr> | 2014-07-18 08:37:24 -0700 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-07-21 13:43:18 +0200 |
| commit | 4ab60c3f32c721e46217e762bcd3e55a8f659c04 (patch) | |
| tree | 5edf608225d61bc595e99fe76c5521501dda1624 /drivers/cpufreq | |
| parent | c410833a3c96b325c68987c2544becad39079c33 (diff) | |
| download | linux-stable-4ab60c3f32c721e46217e762bcd3e55a8f659c04.tar.gz linux-stable-4ab60c3f32c721e46217e762bcd3e55a8f659c04.tar.bz2 linux-stable-4ab60c3f32c721e46217e762bcd3e55a8f659c04.zip | |
cpufreq: intel_pstate: Disable interrupts during MSRs reading
According to Intel 64 and IA-32 Architectures SDM, Volume 3,
Chapter 14.2, "Software needs to exercise care to avoid delays
between the two RDMSRs (for example interrupts)".
So, disable interrupts during reading MSRs IA32_APERF and IA32_MPERF.
This should increase the accuracy of the calculations.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 9d75bd6faf65..ff3c5624972c 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -577,9 +577,12 @@ static inline void intel_pstate_calc_busy(struct cpudata *cpu) static inline void intel_pstate_sample(struct cpudata *cpu) { u64 aperf, mperf; + unsigned long flags; + local_irq_save(flags); rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); + local_irq_restore(flags); aperf = aperf >> FRAC_BITS; mperf = mperf >> FRAC_BITS; |