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Date: Fri, 13 Feb 2004 15:39:36 +0000
From: Joe Thornber <thornber@redhat.com>
To: Lars Marowsky-Bree <lmb@suse.de>
Cc: Joe Thornber <thornber@redhat.com>,
       Linux Mailing List <linux-kernel@vger.kernel.org>, axboe@suse.de
Subject: Re: dm core patches
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On Fri, Feb 13, 2004 at 04:12:14PM +0100, Lars Marowsky-Bree wrote:
> On 2004-02-12T20:13:40,
>    Joe Thornber <thornber@redhat.com> said:
> 
> > I think the main concern now is over the testing of paths.  Sending an
> > io down an inactive path can be very expensive for some hardware
> > configurations.  So I'm considering changing a couple of things:
> > 
> > - Only ever send io to 1 priority group at a time (even test ios).
> >   To test the lower priority groups we'd have to periodically switch to
> >   them and use them for a bit for both test io and proper io.
> 
> You are missing the obvious answer:
> 
> - Periodically checking paths is a user-space issue and doesn't belong
>   into the kernel. User-space gets to handle this policy.

Yes, that is obvious, I had wanted to do failback automatically.  But
pushing it to userland does allow people to write hardware specific
tests.  I'll try it and see what people think.

Thanks,

- Joe