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Date: Thu, 1 Aug 2002 12:05:53 +0200
From: Jens Axboe <axboe@suse.de>
To: martin@dalecki.de
Cc: Petr Vandrovec <VANDROVE@vc.cvut.cz>, linux-kernel@vger.kernel.org
Subject: Re: IDE from current bk tree, UDMA and two channels...
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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.
Good.

> >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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