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Date: Mon, 8 Mar 2010 04:51:43 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Robert Richter <robert.richter@amd.com>
Cc: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
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       Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 0/26] oprofile: Performance counter multiplexing
Message-ID: <20100308035143.GE20695@one.firstfloor.org>
References: <1248800846-25422-1-git-send-email-robert.richter@amd.com> <20090803112220.GA22936@elte.hu> <20090803072522.1d90f15c@infradead.org> <20090804201109.GA21386@elte.hu> <20090805123501.GF14610@erda.amd.com> <84144f020908060031vb48b983m6e6b1b521e01d6aa@mail.gmail.com> <20090806105134.GD11236__37984.4768475325$1249556453$gmane$org@elte.hu> <87ocjcqcdj.fsf@basil.nowhere.org> <20100305164615.GY13205@erda.amd.com>
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> the tests I run with oprofile do not indicate unreliable ring_buffer

Did you try it with callgraph mode? That seems to be worst.

> behavior. Maybe my use cases and loads are different. Can you describe
> a setup where this may happen for sure? What is the impact, do you

Seeing it on very busy 16 CPU and larger systems.

> have lost samples or inconsistent buffer data? Is the data loss in

There are a lot of lost samples, callgraphs are incomplete etc.

> kernel or user space? Also, I am not aware that the ring_buffer is

Not sure.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.