Re: dm core patches

From: Joe Thornber
Date: Fri Feb 13 2004 - 10:41:58 EST


On Fri, Feb 13, 2004 at 04:12:14PM +0100, Lars Marowsky-Bree wrote:
> On 2004-02-12T20:13:40,
> Joe Thornber <thornber@xxxxxxxxxx> 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
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