path: root/Documentation/lockup-watchdogs.txt
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authorBorislav Petkov <>2012-02-07 13:08:52 +0100
committerIngo Molnar <>2012-02-07 13:12:08 +0100
commitc98fdeaa92731308ed80386261fa2589addefa47 (patch)
tree83faddb633c3a70d9eb6157266aa73e3336272c2 /Documentation/lockup-watchdogs.txt
parent52fce956a7568504a1da90c14b9bf2deaad401bd (diff)
x86/sched/perf/AMD: Set sched_clock_stable
Stephane Eranian reported that doing a scheduler latency measurements with perf on AMD doesn't work out as expected due to the fact that the sched_clock() granularity is too coarse, i.e. done in jiffies due to the sched_clock_stable not set, which, if set, would mean that we get to use the TSC as sample source which would give us much higher precision. However, there's no reason not to set sched_clock_stable on AMD because all families from F10h and upwards do have an invariant TSC and have the CPUID flag to prove (CPUID_8000_0007_EDX[8]). Make it so, #1. Signed-off-by: Borislav Petkov <> Cc: Borislav Petkov <> Cc: Venki Pallipadi <> Cc: Peter Zijlstra <> Cc: Stephane Eranian <> Cc: Arnaldo Carvalho de Melo <> Cc: Robert Richter <> Cc: Eric Dumazet <> Cc: Andreas Herrmann <> Link: [ Should any non-standard system break the TSC, we should mark them so explicitly, in their platform init handler, or in a DMI quirk. ] Signed-off-by: Ingo Molnar <>
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