On 10/22/2012 07:23 PM, Stephane Eranian wrote: > On Mon, Oct 22, 2012 at 12:33 PM, Peter Zijlstra <a.p.zijls...@chello.nl> > wrote: >> >> On Mon, 2012-10-22 at 14:11 +0800, Yan, Zheng wrote: >>> + /* LBR callstack does not work well with FREEZE_LBRS_ON_PMI */ >>> + if (!cpuc->lbr_sel || !(cpuc->lbr_sel->config & LBR_CALL_STACK)) >>> + debugctl |= DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; >> > Is this a bug or a feature? > It's a hardware bug. If FREEZE_LBRS_ON_PMI is set, PMI may corrupt the call stack records.
Regards Yan, Zheng >> >> How useful it is without this? How many calls between PMI and us getting >> to intel_pmu_lbr_read()? > > Agreed with Peter. Freeze on PMI is critical for LBR in general. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
