diff options
| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-11-03 16:35:49 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-03 08:50:13 -0700 |
| commit | 941f5f0f6ef5338814145cf2b813cf1f98873e2f (patch) | |
| tree | b5bfebf297b5213cb5ef96af994c5cc84b64e9bb /arch/x86/kernel/cpu/aperfmperf.c | |
| parent | 5cb0512c02ecd7e6214e912e4c150f4219ac78e0 (diff) | |
x86: CPU: Fix up "cpu MHz" in /proc/cpuinfo
Commit 890da9cf0983 (Revert "x86: do not use cpufreq_quick_get() for
/proc/cpuinfo "cpu MHz"") is not sufficient to restore the previous
behavior of "cpu MHz" in /proc/cpuinfo on x86 due to some changes
made after the commit it has reverted.
To address this, make the code in question use arch_freq_get_on_cpu()
which also is used by cpufreq for reporting the current frequency of
CPUs and since that function doesn't really depend on cpufreq in any
way, drop the CONFIG_CPU_FREQ dependency for the object file
containing it.
Also refactor arch_freq_get_on_cpu() somewhat to avoid IPIs and
return cached values right away if it is called very often over a
short time (to prevent user space from triggering IPI storms through
it).
Fixes: 890da9cf0983 (Revert "x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz"")
Cc: stable@kernel.org # 4.13 - together with 890da9cf0983
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/kernel/cpu/aperfmperf.c')
| -rw-r--r-- | arch/x86/kernel/cpu/aperfmperf.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c index 0ee83321a313..957813e0180d 100644 --- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -42,10 +42,6 @@ static void aperfmperf_snapshot_khz(void *dummy) s64 time_delta = ktime_ms_delta(now, s->time); unsigned long flags; - /* Don't bother re-computing within the cache threshold time. */ - if (time_delta < APERFMPERF_CACHE_THRESHOLD_MS) - return; - local_irq_save(flags); rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); @@ -74,6 +70,7 @@ static void aperfmperf_snapshot_khz(void *dummy) unsigned int arch_freq_get_on_cpu(int cpu) { + s64 time_delta; unsigned int khz; if (!cpu_khz) @@ -82,6 +79,12 @@ unsigned int arch_freq_get_on_cpu(int cpu) if (!static_cpu_has(X86_FEATURE_APERFMPERF)) return 0; + /* Don't bother re-computing within the cache threshold time. */ + time_delta = ktime_ms_delta(ktime_get(), per_cpu(samples.time, cpu)); + khz = per_cpu(samples.khz, cpu); + if (khz && time_delta < APERFMPERF_CACHE_THRESHOLD_MS) + return khz; + smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1); khz = per_cpu(samples.khz, cpu); if (khz) |