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authorLen Brown <len.brown@intel.com>2017-04-12 19:44:51 -0400
committerLen Brown <len.brown@intel.com>2017-04-12 20:03:50 -0400
commit95149369c1c28b10f7318dfde54018ab107277d0 (patch)
tree8d220525609dcb1589167c8446731b316a84b67e /tools
parentab23d1146a8e7bd045507fe8a380827dc03e056d (diff)
downloadop-kernel-dev-95149369c1c28b10f7318dfde54018ab107277d0.zip
op-kernel-dev-95149369c1c28b10f7318dfde54018ab107277d0.tar.gz
tools/power turbostat: fix impossibly large CPU%c1 value
Most CPUs do not have a hardware c1 counter, and so turbostat derives c1 residency: c1 = TSC - MPERF - other_core_cstate_counters As it is not possible to atomically read these coutners, measurement jitter can case this calcuation to "go negative" when very close to 0. Turbostat detect that case and simply prints c1 = 0.00% But that check neglected to account for systems where the TSC crystal clock domain and the MPERF BCLK domain are differ by a small amount. That allowed very small negative c1 numbers to escape this check and be printed as huge positve numbers. This code begs for a bit of cleanup, but this patch is the minimal change to fix the issue. Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/power/x86/turbostat/turbostat.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index b0591d0..0ad9661 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -1142,7 +1142,7 @@ delta_thread(struct thread_data *new, struct thread_data *old,
* it is possible for mperf's non-halted cycles + idle states
* to exceed TSC's all cycles: show c1 = 0% in that case.
*/
- if ((old->mperf + core_delta->c3 + core_delta->c6 + core_delta->c7) > old->tsc)
+ if ((old->mperf + core_delta->c3 + core_delta->c6 + core_delta->c7) > (old->tsc * tsc_tweak))
old->c1 = 0;
else {
/* normal case, derive c1 */
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