Messages in this thread | | | Date | Mon, 10 Feb 2003 16:11:44 +0100 | From | Andrea Arcangeli <> | Subject | Re: [PATCH] SFQ disk scheduler |
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On Mon, Feb 10, 2003 at 03:50:01PM +0100, Jens Axboe wrote: > Hi, > > Here's a simple stochastic fairness queueing disk scheduler, for current > 2.5.59-BK. It has known limitations right now, mainly because I didn't > bother making it complete. But it should suffice for some rudimentary > testing, at least.
Cool, that was fast! ;)
> > I'm not going to go into great detail about how it works, see Andrea's > initial post of the paper referenced. This version may not be completely > true to the SFQ concept, but should be close enough I think. It divides > traffic into a fixed number of buckets (64 per default), and perturbs > the hash every 5 seconds (hash shamelessly borrowed from networking atm, > see comment).
I tend to think 5 seconds is too small, 30 sec would be better IMHO (it should be tested at bit).
> To avoid too many disk seeks, when it's time to dispatch requests to the > driver, we round robin all non-empty buckets and grab a single request > from each. These requests are sorted into the dispatch queue. > > For performance reasons, io scheduler request merging is still a > per-queue function (and not per-bucket).
Unsure if it worth, but it probably it won't make that much difference, likely different workloads are working on different part of the disk anyways.
> In closing, let me stress that this version has not really been tested > all that much. It passes simple SCSI and IDE testing, should work on any > hardware basically.
How does it feel?
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