Re: [PATCH] Fall back io scheduler ( Re: [Ext2-devel] Re: Fall back io scheduler for 2.6.15?)

[Jens Axboe <axboe@suse.de>]

On Mon, Jan 16 2006, Mingming Cao wrote:
> On Mon, 2006-01-16 at 09:43 +0100, Jens Axboe wrote:
> > On Fri, Jan 13 2006, Andrew Morton wrote:
> > > Mingming Cao <cmm@us.ibm.com> wrote:
> > > >
> > > > On 2.6.14, the
> > > > fall back io scheduler (if the chosen io scheduler is not found) is set
> > > > to the default io scheduler (anticipatory, in this case), but since
> > > > 2.6.15-rc1, this semanistic is changed to fall back to noop.
> > > 
> > > OK.  And I assume that AS wasn't compiled, so that's why it fell back?
> > > 
> > > I actually thought that elevator= got removed, now we have
> > > /sys/block/sda/queue/scheduler.  But I guess that's not very useful with
> > > CONFIG_SYSFS=n.
> > > 
> > > > Is there any reason to fall back to noop instead of as?  It seems
> > > > anticipatory is much better than noop for ext3 with large sequential
> > > > write tests (i.e, 1G dd test) ...
> > > 
> > > I suspect that was an accident.  Jens?
> > 
> > It is, it makes more sense to fallback to the default of course.
> > 
> 
> How about this one?
> 
> 
> In the case the chosen io scheduler (elevator = "xxx") is not on the
> registered list, fall back to default scheduler makes more sense.
> 
> Signed-off-by: Mingming Cao <cmm@us.ibm.com>

I think you just recreated an identical patch to the one I added this
morning:

http://brick.kernel.dk/git/?p=linux-2.6-block.git;a=commitdiff;h=b7bfcf7cbd58d2a64aa46f3b4bec921e346e604f

:-)

-- 
Jens Axboe