[lkml]   [2001]   [Nov]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [Ext2-devel] disk throughput
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

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:12    [W:1.668 / U:0.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site