Messages in this thread | | | Date | Tue, 27 May 2003 09:58:47 +1000 | From | Nick Piggin <> | Subject | Re: [BK PATCHES] add ata scsi driver |
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Linus Torvalds wrote:
>On Mon, 26 May 2003, Jens Axboe wrote: > >>>Think of all the fairness issues we've had in the elevator code, and >>>realize that the low-level disk probably implements _none_ of those >>>fairness algorithms. >>> >>I think it does, to some extent at least. >> > >I doubt they do a very good job of it. I know of bad cases, even with >"high-end" hardware. Sure, we can hope that it's getting better, but do we >want to bet on it. > > >>>Hmm.. Where does it keep track of request latency for requests that have >>>been removed from the queue? >>> >>Well, it doesn't... >> > >Yeah. Which means that right now _really_ long starvation will show up as >timeouts, while other cases will just show up as bad latency. > There is an elevator notifier which is called on request completion in Andrew's tree (needed for AS io scheduler). This can be used to do what you want.
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