Re: [Ext2-devel] disk throughput

Jens Axboe
2001-11-05T07:26:36Z

On Sun, Nov 04 2001, Andrew Morton wrote:
> 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.
>
> Right, thanks. With the ialloc.c one-liner I didn't touch
> elvtune. Defaults seem fine.
>
> It should the number of requests which are allowed to pass a
> request, not the number of sectors!
>
> Well, you know what I mean: Make it
>
> 1 + nr_sectors_in_request / 1000

That has been tried, performance and latency wasn't good. But yes that
is what we are really looking to account, the number of seeks.
Approximately.

--
Jens Axboe