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

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Date:	Wed, 8 Aug 2007 21:58:32 +0300
From:	Al Boldi <a1426z@...ab.com>
To:	linux-ide@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Disk spin down issue on shut down/suspend to disk

Tejun Heo  wrote:
> Mark Lord wrote:
> > Heh.. I haven't instrumented it yet, but I did discover a bit more about
> > it:
> >
> > The Power-Off_Retract_Count incrmenents *only* when there's data in the
> > on-drive write-cache.  So if I haven't written anything significantly
> > large before suspending, then it often does NOT increment the retract
> > counter.
> >
> > But if I copy a couple of multi-MB files around and then suspend (to
> > RAM), the retract count gets incremented.
> >
> > So I've now just stuck "hdparm -F /dev/sda" into my suspend script,
> > and that cures the problem completely for me.  "-F" does a FLUSH_CACHE,
> > and requires a recent copy of hdparm.
> >
> > Perhaps libata should also do a FLUSH_CACHE before any STANDBYNOW
> > command, prior to entering STR, which is what my script is currently now
> > doing..
> >
> > I'll instrument libata and see what the current sequence is.
>
> Hmmmm.. libata should issue FLUSH CACHE on STR too.  sd_suspend() and
> sd_shutdown() are pretty similar after all.

IMHO, this is a mess because we are essentially trying to work around 
firmware bugs, which may only be solved by having the kernel load a 
user-supplied shutdown sequence, instead of hardcoding it into the kernel.


Thanks!

--
Al

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