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Date: Fri, 10 Dec 2004 22:09:03 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Mark_H_Johnson@raytheon.com
Cc: Amit Shah <amit.shah@codito.com>,
       Karsten Wiese <annabellesgarden@yahoo.de>, Bill Huey <bhuey@lnxw.com>,
       Adam Heath <doogie@debian.org>, emann@mrv.com,
       Gunther Persoons <gunther_persoons@spymac.com>,
       "K.R. Foley" <kr@cybsft.com>, linux-kernel@vger.kernel.org,
       Florian Schmidt <mista.tapas@gmx.net>,
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       Thomas Gleixner <tglx@linutronix.de>,
       Michal Schmidt <xschmi00@stud.feec.vutbr.cz>
Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-15
Message-ID: <20041210210903.GA5864@elte.hu>
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* Mark_H_Johnson@raytheon.com <Mark_H_Johnson@raytheon.com> wrote:

> [1] I still do not get traces where cpu_delay switches CPU's. I only
> get trace output if it starts and ends on a single CPU. [...]

lt001.18RT/lt.02 is such a trace. It starts on CPU#1:

 <unknown-3556  1...1    0µs : find_next_bit (user_trace_start)

and ends on CPU#0:

 <unknown-3556  1...1  247µs : _raw_spin_lock_irqsave (user_trace_stop)

the trace shows a typical migration of an RT task.

(but ... i have to say the debugging overhead is horrible. Please try a
completely-non-debug-non-tracing kernel just to see the difference.)

	Ingo