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From: Andi Kleen <andi@firstfloor.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Theodore Tso <tytso@mit.edu>,
	Arjan van de Ven <arjan@infradead.org>,
	Steven Rostedt <srostedt@redhat.com>
Subject: Re: [PATCH 4/4] trace: profile all if conditionals
Date: Sun, 23 Nov 2008 20:43:07 +0100	[thread overview]
Message-ID: <87iqqei5ys.fsf@basil.nowhere.org> (raw)
In-Reply-To: <20081121071328.462456268@goodmis.org> (Steven Rostedt's message of "Fri, 21 Nov 2008 02:12:17 -0500")

Steven Rostedt <rostedt@goodmis.org> writes:
>
> Miss means the branch was not taken. Hit means the branch was taken.
> The percent is the percentage the branch was taken.

I'm not sure the results are very useful? What would
you do with it?

It seems like a very special case of gcov, but I think I would
rather have the full thing (patches in -mm I think)

> This adds a significant amount of overhead and should only be used
> by those analyzing their system.

Often this can be also done using CPU performance counters. Might 
be a cheaper option. 

-Andi

-- 
ak@linux.intel.com

  parent reply	other threads:[~2008-11-23 19:43 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-21  7:12 [PATCH 0/4] trace: profiling branches Steven Rostedt
2008-11-21  7:12 ` [PATCH 1/4] trace: remove extra assign in branch check Steven Rostedt
2008-11-21  7:12 ` [PATCH 2/4] trace: consolidate unlikely and likely profiler Steven Rostedt
2008-11-21  7:12 ` [PATCH 3/4] trace: branch profiling should not print percent without data Steven Rostedt
2008-11-21  7:12 ` [PATCH 4/4] trace: profile all if conditionals Steven Rostedt
2008-11-21 23:20   ` Andrew Morton
2008-11-21 23:33     ` Steven Rostedt
2008-11-23 12:37       ` Ingo Molnar
2008-11-23 15:48   ` Ingo Molnar
2008-11-23 16:07     ` [PATCH] net/wireless/reg.c: fix Ingo Molnar
2008-11-23 19:43   ` Andi Kleen [this message]
2008-11-23 19:56     ` [PATCH 4/4] trace: profile all if conditionals Steven Rostedt
2008-11-23 20:24       ` Andi Kleen
2008-11-23 20:32         ` Steven Rostedt
2008-11-23 20:51           ` Andi Kleen
2008-11-23 21:38       ` Ingo Molnar
2008-11-30 10:58 ` [PATCH 0/4] trace: profiling branches Daniel Walker
2008-11-30 15:19   ` Steven Rostedt

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