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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-11-03 16:35:49 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-03 08:50:13 -0700
commit941f5f0f6ef5338814145cf2b813cf1f98873e2f (patch)
treeb5bfebf297b5213cb5ef96af994c5cc84b64e9bb /arch
parent5cb0512c02ecd7e6214e912e4c150f4219ac78e0 (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')
-rw-r--r--arch/x86/kernel/cpu/Makefile2
-rw-r--r--arch/x86/kernel/cpu/aperfmperf.c11
-rw-r--r--arch/x86/kernel/cpu/proc.c4
3 files changed, 11 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index c60922a66385..236999c54edc 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -22,7 +22,7 @@ obj-y += common.o
obj-y += rdrand.o
obj-y += match.o
obj-y += bugs.o
-obj-$(CONFIG_CPU_FREQ) += aperfmperf.o
+obj-y += aperfmperf.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o
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)
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 6b7e17bf0b71..4378a729b933 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -78,9 +78,11 @@ static int show_cpuinfo(struct seq_file *m, void *v)
seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
if (cpu_has(c, X86_FEATURE_TSC)) {
- unsigned int freq = cpufreq_quick_get(cpu);
+ unsigned int freq = arch_freq_get_on_cpu(cpu);
if (!freq)
+ freq = cpufreq_quick_get(cpu);
+ if (!freq)
freq = cpu_khz;
seq_printf(m, "cpu MHz\t\t: %u.%03u\n",
freq / 1000, (freq % 1000));