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Date: Thu, 18 Dec 2008 22:16:37 +0100
From: Ingo Molnar <mingo@elte.hu>
To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer
	interrupt infinite loop
Message-ID: <20081218211637.GF24271@elte.hu>
References: <4949A2CC.6040209@gmail.com> <20081218103459.GD10513@elte.hu> <alpine.LFD.2.00.0812181136410.3492@localhost.localdomain> <20081218112216.GE14332@elte.hu> <c62985530812181307k4fc35770x3698101b3981879a@mail.gmail.com>
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* Frédéric Weisbecker <fweisbec@gmail.com> wrote:

> Hmm. No, I just tested by setting 1000 HZ and disabled NOHZ, the system 
> doesn't lockup unless I turn on the function graph tracer.

but that's what we are interested in: the system locks up with HZ=1000 and 
with the tracer on - right?

Which means that it's not some hrtimer problem, but simply the traced 
timer tick takes more than 1 millisecond to execute under this 
virtualization.

	Ingo