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From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Philippe Elie <phil.el@wanadoo.fr>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Oops with oprofile + RT preempt 2.6.11-rc2-RT-V0.7.37-01
Date: Thu, 17 Feb 2005 15:05:26 -0500	[thread overview]
Message-ID: <1108670727.11411.6.camel@krustophenia.net> (raw)
In-Reply-To: <20050213133020.GA16363@elte.hu>

On Sun, 2005-02-13 at 14:30 +0100, Ingo Molnar wrote:
> * Philippe Elie <phil.el@wanadoo.fr> wrote:
> 
> > oprofile_ops.cpu_type == NULL, this has been fixed 3 weeks ago, can
> > you retry with -rc4 ?
> 
> i've uploaded an -rc4 port of the -RT tree half an hour ago (-39-00).
> 

Thanks, -rc4 did fix the bug.

I noticed profiling the kernel with PREEMPT_DESKTOP that mcount and
__mcount add quite a bit of overhead.  Something like .5% CPU each.
Sorry, I didn't save the oprofile output.

So, disable CONFIG_MCOUNT if you want minimal overhead from the RT
patches.  IIRC it was previously stated that the latency tracing
overhead could be mostly avoided by disabling it at runtime.

Lee 


  parent reply	other threads:[~2005-02-17 20:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-13  6:07 Oops with oprofile + RT preempt 2.6.11-rc2-RT-V0.7.37-01 Lee Revell
2005-02-13 13:00 ` Philippe Elie
2005-02-13 13:30   ` Ingo Molnar
2005-02-14  0:55     ` Lee Revell
2005-02-14  1:16       ` Dave Jones
2005-02-17 20:05     ` Lee Revell [this message]
2005-02-17 20:11       ` Ingo Molnar
2005-02-13 13:02 ` Ingo Molnar
2005-02-13 13:15 ` Peter Zijlstra
2005-02-13 13:16   ` Ingo Molnar
2005-02-13 13:20     ` Peter Zijlstra

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