Re: IDE from current bk tree, UDMA and two channels...

From: Jens Axboe (
Date: Thu Aug 01 2002 - 05:05:53 EST

On Thu, Aug 01 2002, Marcin Dalecki wrote:
> >hey that sucks :-)
> Since IDE 111 not any more...

Yeah I just saw that 110 was the 'broken' solution, 111 made it right.

> >seriously, the better way to do this would be to change the q->queuedata
> >to be a pointer to drive instead of the channel.
> ... becouse this is already *done* there :-).


> >that would work, but I think it would seriously starve the other device
> >on the same channel.
> We starve anyway, becouse the kernel isn't real time and we can't
> guarantee "sleeping" for some maximum time and comming back.
> We don't reschedule the kernel during this kind of "sleeping".
> And we can't know that a command on the "mate" will not take
> extraordinary amounts of time. It's only a problem if mixing travan
> tapes with disks on a channel.

I'm thinking about the alternation of the devices so one device can't
starve the other device off the channel.

Jens Axboe

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