linux-kernel - Re: [PATCH v3 00/14] perf, x86: Haswell LBR call stack support

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Message-ID: <530E4B42.5090401@gmail.com>
Date:	Wed, 26 Feb 2014 13:14:58 -0700
From:	David Ahern <dsahern@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	Andi Kleen <andi@...stfloor.org>,
	Stephane Eranian <eranian@...gle.com>,
	"Yan, Zheng" <zheng.z.yan@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [PATCH v3 00/14] perf, x86: Haswell LBR call stack support

On 2/26/14, 12:25 PM, Andy Lutomirski wrote:
> On Wed, Feb 26, 2014 at 11:19 AM, David Ahern <dsahern@...il.com> wrote:
>> On 2/26/14, 11:59 AM, Andy Lutomirski wrote:
>>
>>> I wonder if anyone who uses perf for userspace profiling *ever* uses
>>> FP and gets away with it.  There's precious little userspace software
>>> compiled with frame pointers these days on most architectures.
>>
>>
>> yes and yes. With control over the entire stack we are making sure
>> frame-pointers are enabled as much as possible.
>>
>
> I'm curious why.

Is there some reason not to enable frame pointers?

fp method has much less overhead than dwarf, and good, clear callchains 
are important.

>
> Maybe this should be a config option.  Anyone using a standard distro
> is running a nearly completely frame-pointer-omitted userspace these
> days.

Does WRL or Yocto fall into that 'standard distro' comment? Fairly easy 
to enable frame-pointers.

David
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