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authorLinus Torvalds <torvalds@linux-foundation.org>2017-11-10 11:19:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-10 11:19:11 -0800
commitea0ee33988778fb73e4f45e7c73fb735787e2f32 (patch)
tree45ebd3e4347a879157dab48b2bc88f9bf2cf9286
parent3e81277a6edd6b568c3a091a372dfe6368697b21 (diff)
Revert "x86: CPU: Fix up "cpu MHz" in /proc/cpuinfo"
This reverts commit 941f5f0f6ef5338814145cf2b813cf1f98873e2f. Sadly, it turns out that we really can't just do the cross-CPU IPI to all CPU's to get their proper frequencies, because it's much too expensive on systems with lots of cores. So we'll have to revert this for now, and revisit it using a smarter model (probably doing one system-wide IPI at open time, and doing all the frequency calculations in parallel). Reported-by: WANG Chao <chao.wang@ucloud.cn> Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-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, 6 insertions, 11 deletions
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 236999c54edc..c60922a66385 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-y += aperfmperf.o
+obj-$(CONFIG_CPU_FREQ) += aperfmperf.o
obj-$(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 957813e0180d..0ee83321a313 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -42,6 +42,10 @@ 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);
@@ -70,7 +74,6 @@ 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)
@@ -79,12 +82,6 @@ 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 4378a729b933..6b7e17bf0b71 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -78,11 +78,9 @@ 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 = arch_freq_get_on_cpu(cpu);
+ unsigned int freq = cpufreq_quick_get(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));

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