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SubjectRe: disk head scheduling
On Mon, Mar 22, 1999 at 12:17:05AM +0100, Gerard Roudier wrote:
>
>
> On Sun, 21 Mar 1999, Linus Torvalds wrote:
>
> > Anyway, the problem with the basic block interface is that it is currently
> > locked to using the major number of a device as the index into the queue.
> > That wasn't really how it was _meant_ to be: it was just that the early
> > devices had a nice "one major number for one controller" setup, so the 1:1
> > mapping was the simplest one.
>
> But the code seems to plug the major, thus the controller, but says that
> it plugs the device. This perhaps didn't affected performances with early
> controllers. Now, it is allowed to have queues based on kdev_t value, but
> the code still seems to plug the major. This looks too me like some
> incomplete enhancement, btw.

I guess that could be changed to use the queue() function, with unplug_device
getting a parameter specifying which device is to be unplugged, but we would
need to `allocate' plug_tq's from somewhere rather than just statically
associating one with each major device.

(Also, raid5.c seems to be wanting to muck about with unplug_device: it's
currently inside of a #if 0).

-- arvind

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