linux-kernel - Re: Disk spin down issue on shut down/suspend to disk

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Message-ID: <20070809150634.GA3926@ucw.cz>
Date:	Thu, 9 Aug 2007 15:06:35 +0000
From:	Pavel Machek <pavel@....cz>
To:	Tejun Heo <htejun@...il.com>
Cc:	Robert Hancock <hancockr@...w.ca>,
	Michael Sedkowski <sedmich@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Henrique de Moraes Holschuh <hmh@....eng.br>,
	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	linux-acpi@...r.kernel.org, Thomas Renninger <trenn@...e.de>
Subject: Re: Disk spin down issue on shut down/suspend to disk

Hi!

> >> Oh... crap, so acpi wants to sync cache on shutdown.  I wonder whether
> >> it spins down the disk correctly.  Does emergency unload count increase
> >> after each power down?  Also, please post the result of 'dmidecode'.
> > 
> > I know that my Compaq X1000-series laptop does do some kind of ACPI
> > games with the disk on ACPI power off (I assume it is putting the disk
> > in standby before power-off at least). It also does this if you boot
> > into DOS, GRUB, etc. and then hit the power button. Could be if the disk
> > is dumb enough to spin up for sync cache and standby when there is
> > nothing to flush, and the kernel does its own standby, this could cause
> > an extra spinup/down..
> 
> Yeah, that seems to be what's going on.  I don't think we have any other
> choice than blacklisting those notebooks.  This is a mess.  How does the
> other OS cope with this?
> 
> I'm thinking about using DMI vendor/product match to detect the affected
> systems but I think it would be better to match the ACPI implementation
> directly.  Is there a way to match specific ACPI implementation?

Well.. unless they use some SMM trick, it is ACPI AML code telling
kernel to spin the disk down. I guess we could detect that, and simply
ignore the request.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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