Re: CFS not suitable for desktop computers

Mike Galbraith
2009-05-05T05:42:22Z

On Mon, 2009-05-04 at 15:01 -0600, Chris Friesen wrote:
> Nico Schümann wrote:
> > Thank you Ray Lee and Mike Galbraith for your responses, I ran the
> > script and attached its gathered information.
> >
> > Mike Galbraith wrote:
> >> How hard is hard? Can you describe the loads you're having trouble
> >> with, and the hardware you're running them on?
> >>
> >>
> > I could reproduce "hard" load by just compiling the linux kernel, make
> > -j3 while reading mails with Thunderbird, which is not that hard
> > foreground load. Thunderbird starts reacting really slowly while compiling.
>
> I wonder if this could be related to I/O rather than the task scheduler
> proper.

That's something I was wondering as well, particularly when I noticed
he's using data=journal and anticipatory io-scheduler.

Doing some testing with different journal modes and io-schedulers
recently, I found loads where anticipatory didn't do very well compared
to cfq, and journal mode can make a tremendous difference ala..

time ./postmark < config

ordered writeback guarded journal
real 11m18.752s 3m5.160s 3m1.367s 15m18.610s
user 0m5.672s 0m6.220s 0m5.976s 0m6.856s
sys 0m26.094s 0m20.965s 0m21.673s 0m20.969s

real 9m33.922s 2m53.984s 3m6.284s 15m12.969s
user 0m5.700s 0m5.976s 0m6.356s 0m6.980s
sys 0m26.682s 0m21.413s 0m20.717s 0m19.641s

real 10m8.766s 3m0.382s 2m58.714s 15m33.400s
user 0m5.608s 0m6.080s 0m6.232s 0m6.776s
sys 0m27.130s 0m21.041s 0m21.709s 0m19.489s

-Mike