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On Mon, Nov 05, 2001 at 08:06:35AM +0100, Jens Axboe wrote: > On Sun, Nov 04 2001, Andrew Morton wrote: > > The meaning of the parameter to elvtune is a complete mystery, and the > > code is uncommented crud (tautology). So I just used -r20000 -w20000. > > It's the number of sectors that are allowed to pass a request on the > queue, because of merges or inserts before that particular request. So > you want lower than that probably, and you want READ latency to be > smaller than WRITE latency too. The default I set is 8192/16384 iirc, so > go lower than this -- -r512 -w1024 or even lower just to check the > results. > Does the elevator do better with powers of two? > > This was based on observing the request queue dynamics. We frequently > > fail to merge requests which really should be merged regardless of > > latency. Bumping the elvtune settings fixed it all. But once the > > fs starts writing data out contiguously it's all academic. > > Interesting, the 2.5 design prevents this since it doesn't account > merges as a penalty (like a seek). I can do something like that for 2.4 > too, I'll do a patch for you to test. > I'd be very interested in this patch. Can you post it pubically? > -- > Jens Axboe > Mike - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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