linux-kernel - Re: [PATCH 1/1] perf, x86: bug fix for cycles:p and cycles:pp on SLM

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Message-ID: <20141215151807.GA29390@twins.programming.kicks-ass.net>
Date:	Mon, 15 Dec 2014 16:18:07 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	kan.liang@...el.com
Cc:	linux-kernel@...r.kernel.org, ak@...ux.intel.com
Subject: Re: [PATCH 1/1] perf, x86: bug fix for cycles:p and cycles:pp on SLM

On Mon, Dec 08, 2014 at 06:27:43AM -0800, kan.liang@...el.com wrote:
> From: Kan Liang <kan.liang@...el.com>
> 
> cycles:p and cycles:pp don't work on SLM since 86a0446

The canonical format for referencing commits is:
  86a04461a99f ("perf/x86: Revamp PEBS event selection")

> This regression issue is because UOPS_RETIRED.ALL is not a PEBS event on SLM.

Nor is it actually the alias used, afaict SLM uses
intel_pebs_aliases_core2().

> According to pebs_aliases, INST_RETIRED.ANY_P (a PEBS capable event) can be
> used as an alternative way to count cycles. Roll back the pebs_constraints to
> use INST_RETIRED.ANY_P.

Furthermore the counter mask of 0xf seems wrong too, and you've indeed
corrected that too (to 0x01, seeing how the SLM only has PEBS on cnt0).

Fixes: 86a04461a99f ("perf/x86: Revamp PEBS event selection")
> Signed-off-by: Kan Liang <kan.liang@...el.com>
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