linux-kernel - Re: [RFC PATCH 0/7] perf, x86: Reduce lbr_sel

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Message-ID: <20131004105535.GH3081@twins.programming.kicks-ass.net>
Date:	Fri, 4 Oct 2013 12:55:35 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	linux-kernel@...r.kernel.org, eranian@...gle.com,
	andi@...stfloor.org
Subject: Re: [RFC PATCH 0/7] perf, x86: Reduce lbr_sel_map size

On Thu, Sep 26, 2013 at 04:28:06PM +0800, Yan, Zheng wrote:
> From: "Yan, Zheng" <zheng.z.yan@...el.com>
> 
> Haswell has a new feature that utilizes the existing Last Branch Record
> facility to record call chains. When the feature is enabled, function
> call will be collected as normal, but as return instructions are executed
> the last captured branch record is popped from the on-chip LBR registers.
> The LBR call stack facility can help perf to get call chains of progam 
> without frame pointer. When perf tool requests PERF_SAMPLE_CALLCHAIN +
> PERF_SAMPLE_BRANCH_USER, this feature is dynamically enabled by default.
> This feature can be disabled/enabled through an attribute file in the cpu
> pmu sysfs directory.
> 
> The main change since previous patch series is:
>  Patch 3 introduces PMU context switch callback, and uses the callback to
>  unify the flush branch stack codeo.
> 
>  Patch 4 uses the context switch callback to save/restore the LBR stack.

>From what I can tell this is the exact same drivel I rejected earlier.

Same shitty changelogs, same shitty code.

Do not waste my time like this.
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