diff options
| -rw-r--r-- | arch/x86/kernel/cpu/aperfmperf.c | 77 | ||||
| -rw-r--r-- | fs/proc/cpuinfo.c | 6 | ||||
| -rw-r--r-- | include/linux/cpufreq.h | 1 |
3 files changed, 35 insertions, 49 deletions
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c index 963c0697a92b..e9d2da7effc9 100644 --- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -101,49 +101,6 @@ static bool aperfmperf_snapshot_cpu(int cpu, ktime_t now, bool wait) return time_delta <= APERFMPERF_STALE_THRESHOLD_MS; } -unsigned int aperfmperf_get_khz(int cpu) -{ - if (!cpu_khz) - return 0; - - if (!boot_cpu_has(X86_FEATURE_APERFMPERF)) - return 0; - - if (!housekeeping_cpu(cpu, HK_TYPE_MISC)) - return 0; - - if (rcu_is_idle_cpu(cpu)) - return 0; /* Idle CPUs are completely uninteresting. */ - - aperfmperf_snapshot_cpu(cpu, ktime_get(), true); - return per_cpu(samples.khz, cpu); -} - -void arch_freq_prepare_all(void) -{ - ktime_t now = ktime_get(); - bool wait = false; - int cpu; - - if (!cpu_khz) - return; - - if (!boot_cpu_has(X86_FEATURE_APERFMPERF)) - return; - - for_each_online_cpu(cpu) { - if (!housekeeping_cpu(cpu, HK_TYPE_MISC)) - continue; - if (rcu_is_idle_cpu(cpu)) - continue; /* Idle CPUs are completely uninteresting. */ - 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) { struct aperfmperf_sample *s = per_cpu_ptr(&samples, cpu); @@ -530,6 +487,40 @@ void arch_scale_freq_tick(void) scale_freq_tick(acnt, mcnt); } +/* + * Discard samples older than the define maximum sample age of 20ms. There + * is no point in sending IPIs in such a case. If the scheduler tick was + * not running then the CPU is either idle or isolated. + */ +#define MAX_SAMPLE_AGE ((unsigned long)HZ / 50) + +unsigned int aperfmperf_get_khz(int cpu) +{ + struct aperfmperf *s = per_cpu_ptr(&cpu_samples, cpu); + unsigned long last; + unsigned int seq; + u64 acnt, mcnt; + + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)) + return 0; + + do { + seq = raw_read_seqcount_begin(&s->seq); + last = s->last_update; + acnt = s->acnt; + mcnt = s->mcnt; + } while (read_seqcount_retry(&s->seq, seq)); + + /* + * Bail on invalid count and when the last update was too long ago, + * which covers idle and NOHZ full CPUs. + */ + if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE) + return 0; + + return div64_u64((cpu_khz * acnt), mcnt); +} + static int __init bp_init_aperfmperf(void) { if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)) diff --git a/fs/proc/cpuinfo.c b/fs/proc/cpuinfo.c index 419760fd77bd..f38bda5b83ec 100644 --- a/fs/proc/cpuinfo.c +++ b/fs/proc/cpuinfo.c @@ -5,14 +5,10 @@ #include <linux/proc_fs.h> #include <linux/seq_file.h> -__weak void arch_freq_prepare_all(void) -{ -} - extern const struct seq_operations cpuinfo_op; + static int cpuinfo_open(struct inode *inode, struct file *file) { - arch_freq_prepare_all(); return seq_open(file, &cpuinfo_op); } diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 35c7d6db4139..d5595d57f4e5 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -1199,7 +1199,6 @@ static inline void sched_cpufreq_governor_change(struct cpufreq_policy *policy, struct cpufreq_governor *old_gov) { } #endif -extern void arch_freq_prepare_all(void); extern unsigned int arch_freq_get_on_cpu(int cpu); #ifndef arch_set_freq_scale |