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| author |   Thomas Gleixner <tglx@linutronix.de> | 2022-04-25 17:45:42 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-04-27 20:22:20 +0200 |
| commit | fb4c77c21aba03677f283acda3cae748ef866abf (patch) | |
| tree | 2d3689f56b007492a481ba10ae6f4951158e9c8f | |
| parent | x86/aperfmperf: Replace arch_freq_get_on_cpu() (diff) | |
| download | linux-dev-fb4c77c21aba03677f283acda3cae748ef866abf.tar.xz linux-dev-fb4c77c21aba03677f283acda3cae748ef866abf.zip | |
x86/aperfmperf: Integrate the fallback code from show_cpuinfo()
Due to the avoidance of IPIs to idle CPUs arch_freq_get_on_cpu() can return
0 when the last sample was too long ago.
show_cpuinfo() has a fallback to cpufreq_quick_get() and if that fails to
return cpu_khz, but the readout code for the per CPU scaling frequency in
sysfs does not.
Move that fallback into arch_freq_get_on_cpu() so the behaviour is the same
when reading /proc/cpuinfo and /sys/..../cur_scaling_freq.
Suggested-by: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Doug Smythies <dsmythies@telus.net>
Link: https://lore.kernel.org/r/87pml5180p.ffs@tglx
| -rw-r--r-- | arch/x86/kernel/cpu/aperfmperf.c | 10 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/proc.c | 7 |
2 files changed, 8 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c index b15c884c4cbf..1f60a2b27936 100644 --- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -405,12 +405,12 @@ void arch_scale_freq_tick(void) unsigned int arch_freq_get_on_cpu(int cpu) { struct aperfmperf *s = per_cpu_ptr(&cpu_samples, cpu); + unsigned int seq, freq; unsigned long last; - unsigned int seq; u64 acnt, mcnt; if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)) - return 0; + goto fallback; do { seq = raw_read_seqcount_begin(&s->seq); @@ -424,9 +424,13 @@ unsigned int arch_freq_get_on_cpu(int cpu) * which covers idle and NOHZ full CPUs. */ if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE) - return 0; + goto fallback; return div64_u64((cpu_khz * acnt), mcnt); + +fallback: + freq = cpufreq_quick_get(cpu); + return freq ? freq : cpu_khz; } static int __init bp_init_aperfmperf(void) diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c index 0a0ee55830c7..099b6f0d96bd 100644 --- a/arch/x86/kernel/cpu/proc.c +++ b/arch/x86/kernel/cpu/proc.c @@ -86,12 +86,7 @@ static int show_cpuinfo(struct seq_file *m, void *v) if (cpu_has(c, X86_FEATURE_TSC)) { 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)); + seq_printf(m, "cpu MHz\t\t: %u.%03u\n", freq / 1000, (freq % 1000)); } /* Cache size */ |