linux-kernel - Re: BIOS THRM-Throttling and driver timings

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Message-Id: <1160343907.3000.183.camel@laptopd505.fenrus.org>
Date:	Sun, 08 Oct 2006 23:45:06 +0200
From:	Arjan van de Ven <arjan@...radead.org>
To:	Pavel Machek <pavel@....cz>
Cc:	Keith Chew <keith.chew@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: BIOS THRM-Throttling and driver timings

On Sun, 2006-10-08 at 23:18 +0200, Pavel Machek wrote:
> Hi!
> 
> > > We have a motherboard that has Thermal Throttling in the BIOS (which
> > > we cannot disable). This causes the CPU usage to go up and down when
> > > the CPU temperature reaches (and stays around) the Throttling
> > > temperature point.
> > > 
> > > What we would like to know is whether this will affect the timings in
> > > drivers, eg the wireless drivers we are using. What can we check in
> > > drivers' code that will tell us that its operations may be affected
> > > the throttling?
> > > 
> > > In the past few days, we noticed that some of the linux units we
> > > deployed freezes after deveral hours of operation, we are now trying
> > > to reproduce the problem in our test environment. Some insight on the
> > > affect of throttling will help us narrow down the search.
> 
> > in general linux should be ok with this happening. However for specific
> > cases... you'll need to provide more information; you're not
> > mentioning
> 
> Really? AFAICT P4 will happily slow down behind our backs, making at
> least udelays() with interrupts disabled sleep for too long.

it will during thermal throttle yes. but udelay() and co as API never
have  been super accurate; they mostly promise at least this much delay



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