Re: [PATCH 1/6] perf, x86: Basic Haswell LBR call stack support

From: Peter Zijlstra
Date: Mon Oct 22 2012 - 06:33:40 EST


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;

How useful it is without this? How many calls between PMI and us getting
to intel_pmu_lbr_read()?
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