From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: syncing the disks when entering sleep
Date: Fri, 22 Jan 2010 21:49:46 +0100
Message-ID: <201001222149.46839.rjw@sisk.pl>
References: <76FA3B279DD9DA48896E2B404944957204E0B241@USA7061MS02.na.xerox.net>
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To: "Leisner, Martin" <Martin.Leisner@xerox.com>
Cc: linux-pm@lists.linux-foundation.org
List-Id: linux-pm@vger.kernel.org

On Friday 22 January 2010, Leisner, Martin wrote:
> I noticed when we enter sleep states, it seems there's always a
> sys_sync given.
> 
> When having an embedded system doing WOL (already in laptop mode to
> cache
> all the writes), it reasonable to wake up dozens of times of day and
> quickly go back to sleep.  If the disk is not spun up,
> and there's some work to be done, won't the sys_sync spin up the disk
> before going to sleep?
> 
> It would be good to have a knob (in /sys) you can tweak from usespace to
> 
> configure the behavior of whether you want to do a sync when entering
> sleep.
> 
> The ideal behavior would be:
> 
>     if(disk is spun up)
>         then let the sync happen

I'm not against that.  Patch welcome. :-)

Rafael