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

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Message-ID: <1350902016.2768.85.camel@twins>
Date:	Mon, 22 Oct 2012 12:33:36 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	linux-kernel@...r.kernel.org, eranian@...gle.com,
	ak@...ux.intel.com
Subject: Re: [PATCH 1/6] perf, x86: Basic Haswell LBR call stack support

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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