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.
Signed-off-by: Giovanni Gherdovich <ggherdov...@suse.cz>
Suggested-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance")
---
arch/x86/kernel/smpboot.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index d660966d7de7..fe154c8226ba 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -2001,9 +2001,11 @@ static bool intel_set_max_freq_ratio(void)
/*
* 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;
}
--
2.16.4
