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Diffstat (limited to 'arch/x86/kernel/cpu/aperfmperf.c')
-rw-r--r--arch/x86/kernel/cpu/aperfmperf.c74
1 files changed, 52 insertions, 22 deletions
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index 957813e0180d..7eba34df54c3 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -14,6 +14,8 @@
#include <linux/percpu.h>
#include <linux/smp.h>
+#include "cpu.h"
+
struct aperfmperf_sample {
unsigned int khz;
ktime_t time;
@@ -24,7 +26,7 @@ struct aperfmperf_sample {
static DEFINE_PER_CPU(struct aperfmperf_sample, samples);
#define APERFMPERF_CACHE_THRESHOLD_MS 10
-#define APERFMPERF_REFRESH_DELAY_MS 20
+#define APERFMPERF_REFRESH_DELAY_MS 10
#define APERFMPERF_STALE_THRESHOLD_MS 1000
/*
@@ -38,8 +40,6 @@ static void aperfmperf_snapshot_khz(void *dummy)
u64 aperf, aperf_delta;
u64 mperf, mperf_delta;
struct aperfmperf_sample *s = this_cpu_ptr(&samples);
- ktime_t now = ktime_get();
- s64 time_delta = ktime_ms_delta(now, s->time);
unsigned long flags;
local_irq_save(flags);
@@ -57,38 +57,68 @@ static void aperfmperf_snapshot_khz(void *dummy)
if (mperf_delta == 0)
return;
- s->time = now;
+ s->time = ktime_get();
s->aperf = aperf;
s->mperf = mperf;
-
- /* If the previous iteration was too long ago, discard it. */
- if (time_delta > APERFMPERF_STALE_THRESHOLD_MS)
- s->khz = 0;
- else
- s->khz = div64_u64((cpu_khz * aperf_delta), mperf_delta);
+ s->khz = div64_u64((cpu_khz * aperf_delta), mperf_delta);
}
-unsigned int arch_freq_get_on_cpu(int cpu)
+static bool aperfmperf_snapshot_cpu(int cpu, ktime_t now, bool wait)
{
- s64 time_delta;
- unsigned int khz;
+ s64 time_delta = ktime_ms_delta(now, per_cpu(samples.time, cpu));
+
+ /* Don't bother re-computing within the cache threshold time. */
+ if (time_delta < APERFMPERF_CACHE_THRESHOLD_MS)
+ return true;
+
+ smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, wait);
+
+ /* Return false if the previous iteration was too long ago. */
+ return time_delta <= APERFMPERF_STALE_THRESHOLD_MS;
+}
+unsigned int aperfmperf_get_khz(int cpu)
+{
if (!cpu_khz)
return 0;
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;
+ aperfmperf_snapshot_cpu(cpu, ktime_get(), true);
+ return per_cpu(samples.khz, cpu);
+}
- smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1);
- khz = per_cpu(samples.khz, cpu);
- if (khz)
- return khz;
+void arch_freq_prepare_all(void)
+{
+ ktime_t now = ktime_get();
+ bool wait = false;
+ int cpu;
+
+ if (!cpu_khz)
+ return;
+
+ if (!static_cpu_has(X86_FEATURE_APERFMPERF))
+ return;
+
+ for_each_online_cpu(cpu)
+ if (!aperfmperf_snapshot_cpu(cpu, now, false))
+ wait = true;
+
+ if (wait)
+ msleep(APERFMPERF_REFRESH_DELAY_MS);
+}
+
+unsigned int arch_freq_get_on_cpu(int cpu)
+{
+ if (!cpu_khz)
+ return 0;
+
+ if (!static_cpu_has(X86_FEATURE_APERFMPERF))
+ return 0;
+
+ if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true))
+ return per_cpu(samples.khz, cpu);
msleep(APERFMPERF_REFRESH_DELAY_MS);
smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1);