Re: 2.6.0 performance problems

[Roger Luethi <rl@hellgate.ch>]

On Wed, 31 Dec 2003 12:21:19 +0100, Jens Axboe wrote:
> > Thanks. 2.5.39 alone will do, actually. I'm just curious how far the
> > similarity between qsbench and bk export goes.
> 
> 2.5.39 is when the deadline io scheduler was merged. How do you define
> the qsbench suckiness?

2.5.39 was the biggest regression for qsbench (fixed later, most notably
in 2.5.41). 2.5.39 was a significant improvement for efax ("fixed"
in 2.5.43).

All I'm doing here is reading the graph I posted at:
http://hellgate.ch/bench/thrash.tar.gz

For the systematic testing, I used "qsbench -p 4 -m 96" on a 256 MB
machine. This allowed the kernel to achieve high performance with
unfairness -- that's what 2.4 does: One process dominates all others
and finishes very early, taking away most of the memory pressure.
The spike for qsbench in 2.5.39 remains if only one process is forked
(-p1 -m 384), though.

I asked for the bk export numbers with 2.5.39 because I'm curious how
close to qsbench the behavior really is.

> Do you have numbers for 2.4.x and 2.6.1-rc with
> the various io schedulers (it would be interesting to see stock,
> elevator=deadline, and elevator=noop).

I planned to compare the io schedulers in 2.6.0 anyway. Do you expect
different numbers for a recent bk snapshot?

Roger