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SubjectRe: disk head scheduling
Date
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Eric Youngdale wrote:
>
> Forgive me for jumping in late on this one - I have just one
> observation. It isn't clear to me that it would work well to have a
> single queue per device, at least in all cases. Some host adapters have
> limits (sometimes in hardware, not just a driver limitation) on the
> maximum number of outstanding commands, and it would take a bit of hacking
> to find a way to pick commands from multiple queues in order to prevent
> starvation. For host adapters that have no such limits, then a per-device
> queue would work just fine.

Indeed, That's why Linus suggests a function that returns queue to put
the request into.

That way a controller can elect to override the default of one queue
per device.

Roger.

--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
------ Microsoft gives you Windows, Linux gives you the whole house ------


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