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| author |   Giovanni Gherdovich <ggherdovich@suse.cz> | 2020-05-31 20:24:52 +0200 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2020-06-15 14:10:02 +0200 |
| commit | 51beea8862a3095559862df39554f05042e1195b (patch) | |
| tree | def1b72a6ceaf020d21c10721ca5c0891bf9cce4 /arch/x86/kernel/smpboot.c | |
| parent | x86, sched: check for counters overflow in frequency invariant accounting (diff) | |
| download | linux-dev-51beea8862a3095559862df39554f05042e1195b.tar.xz linux-dev-51beea8862a3095559862df39554f05042e1195b.zip | |
x86, sched: Bail out of frequency invariance if turbo frequency is unknown
There may be CPUs that support turbo boost but don't declare any turbo
ratio, i.e. their MSR_TURBO_RATIO_LIMIT is all zeroes. In that condition
scale-invariant calculations can't be performed.
Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance")
Suggested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://lkml.kernel.org/r/20200531182453.15254-3-ggherdovich@suse.cz
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 18d292fc466c..20e1cea262e4 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -2002,9 +2002,11 @@ out: /* * Some hypervisors advertise X86_FEATURE_APERFMPERF * but then fill all MSR's with zeroes. + * Some CPUs have turbo boost but don't declare any turbo ratio + * in MSR_TURBO_RATIO_LIMIT. */ - if (!base_freq) { - pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n"); + if (!base_freq || !turbo_freq) { + pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n"); return false; } |