linux-kernel - Re: [RT] [RFC] simple SMI detector

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Message-ID: <20090125225205.GA3783@monkey.beaverton.ibm.com>
Date:	Sun, 25 Jan 2009 14:52:05 -0800
From:	Mike Kravetz <kravetz@...ibm.com>
To:	Jon Masters <jcm@...hat.com>
Cc:	linux-rt-users@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	williams <williams@...hat.com>,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Subject: Re: [RT] [RFC] simple SMI detector

On Fri, Jan 23, 2009 at 05:55:12PM -0500, Jon Masters wrote:
> This patch adds the module smi_detector under drivers/misc
> 
> Code from Jon Masters with small changes from Luis Goncalves and
> documentation from Clark Williams.

Good work Jon.  I think something like this will be helpful.

Any reason why you could not do SMI detection in user level code running
at the highest RT priority?  If something is running at the highest RT
priority, it should not be preempted by anything.  Right?  In the past,
we discoved discovered periodic SMIs on some hardware platforms by running
a user level process in an infinite loop sampling the clock and reporting
unexpected delays.  Of course, this does hog an entire CPU.

-- 
Mike
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