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Date: Wed, 05 Jun 2002 03:55:19 -0700
From: Andrew Morton <akpm@zip.com.au>
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To: Jens Axboe <axboe@suse.de>
CC: Xavier Bestel <xavier.bestel@free.fr>,
        Andreas Dilger <adilger@clusterfs.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: [rfc] "laptop mode"
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Jens Axboe wrote:
> 
> On Wed, Jun 05 2002, Xavier Bestel wrote:
> > Le mer 05/06/2002 ? 01:43, Andrew Morton a ?crit :
> >
> > > Also, it has been suggested that the feature become more fully-fleshed,
> > > to support desktops with one disk spun down, etc.  It's not really
> > > rocket science to do that - the `struct backing_dev_info' gives
> > > a specific communication channel between the high-level VFS code and
> > > the request queue.  But that would require significantly more surgery
> > > against the writeback code, so I'm fishing for requirements here.  If
> > > the current (simple) patch is sufficient then, well, it is sufficient.
> >
> > Have per-disk laptop-mode, so that some user-mode proggy (e.g. hotplug)
> > could decide what to do.
> 
> And get rid of disk_spun_up(), make it a queue flag instead and signal
> the spin up before calling the request_fn instead of shoving it inside
> the driver request_fn's.

Then writes to the ramdisk would cause a spinup.

Yes, it could be per-queue.  That would add complexity to
the already-murky fs/fs-writeback.c.  It that justifiable?

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