From: Peter Zijlstra <peterz@infradead.org>
To: kan.liang@intel.com
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, acme@kernel.org,
ak@linux.intel.com
Subject: Re: [RFC PATCH 1/1] proc: introduce /proc/<pid>/lbr_stack
Date: Mon, 23 Feb 2015 17:49:57 +0100 [thread overview]
Message-ID: <20150223164957.GB5029@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1424663021-82663-1-git-send-email-kan.liang@intel.com>
On Mon, Feb 23, 2015 at 03:43:41AM +0000, kan.liang@intel.com wrote:
> From: Kan Liang <kan.liang@intel.com>
>
> Haswell has a new feature that utilizes the existing Last Branch Record
> facility to record call chains. It has been implemented in perf. The
> call chains information is saved during perf event context.
>
> This patch exposes a /proc/<pid>/lbr_stack file that shows the saved LBR
> call chain information.
But why? I mean, this thing is only useful if you have a concurrently
running perf record that selects the LBR-stack stuff.
And if you have that, you might as well look at its output instead. Why
add this unconditional proc file that doesn't function on its own?
next prev parent reply other threads:[~2015-02-23 16:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-23 3:43 kan.liang
2015-02-23 16:49 ` Peter Zijlstra [this message]
2015-02-23 17:44 ` Andi Kleen
2015-02-27 7:58 ` Peter Zijlstra
2015-02-27 17:54 ` Andi Kleen
2015-02-27 22:05 ` Peter Zijlstra
2015-02-27 23:57 ` Andi Kleen
2015-02-28 10:18 ` Peter Zijlstra
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