linux-kernel - Re: [PATCH 2/2] perf_counter: detect debugfs location

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Date:	Tue, 21 Jul 2009 10:01:40 -0700
From:	Ray Lee <ray-lk@...rabbit.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Jason Baron <jbaron@...hat.com>, mingo@...e.hu,
	linux-kernel@...r.kernel.org, paulus@...ba.org,
	a.p.zijlstra@...llo.nl, fweisbec@...il.com
Subject: Re: [PATCH 2/2] perf_counter: detect debugfs location

On Tue, Jul 21, 2009 at 9:44 AM, Steven Rostedt<rostedt@...dmis.org> wrote:
>
> On Tue, 21 Jul 2009, Ray Lee wrote:
>
>> On Tue, Jul 21, 2009 at 9:20 AM, Jason Baron <jbaron@...hat.com> wrote:
>> >
>> > Search for the debugfs filesystem in /proc/mounts, but also allows the user to
>> > specify '--debugfs-dir=blah' or set the environment variable: 'PERF_DIR_DEBUGFS'
>>
>> > -static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
>>
>> There are server systems out there that run with thousands of mounts.
>> It would be kinder to the users of those systems (ie, faster perf
>> startup) if you only went rooting around /proc/mounts if opening the
>> default location failed.
>
> Well, those that have thousand of mounts could probably get away with
> setting PERF_DIR_DEBUGFS in /etc/profile.

The intent of the patch is obviously to try to Do The Right Thing by
default. I think that's great. I just think it should DT(fast and)RT
instead.

> But, a simple stat("/sys/kernel/debug/tracing") should be easy enough.

<nod>
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