Messages in this thread | | | Subject | Re: disk head scheduling | Date | Tue, 23 Mar 1999 13:45:22 +0100 (MET) | From | (Rogier Wolff) |
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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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