Re: Question about fair schedulers

[Alberto Gonzalez <info@gnebu.es>]

On Saturday 23 June 2007, Kyle Moffett wrote:
> On Jun 22, 2007, at 18:07:15, Alberto Gonzalez wrote:
> > P.S: As a second thought, a fair scheduler could behave really good
> > in other scenarios, like a server running a busy forum on apache
> > +mysql+php. Besides, this is a more real world scenario (and easier
> > to benchmark). Why aren't people testing these schedulers under
> > this kind of load?
>
> That kind of load is boring precisely because it doesn't care about
> interactivity.  CFS/SD aren't a whole lot different from mainline-
> without-interactivity in that respect, precisely because the latency
> of the network is between ten and a hundred times more than the
> latency of the scheduler.  The only time it really matters is with
> desktops where users care about smoothness.

Well, I've just seen some benchmarks of this kind with CFS and it does make a 
difference. The scalability problem with MySQL seems to get solved with this 
scheduler. However, the peak throughput is quite lower than with the same 
kernel/glibc version and mainline scheduler.

http://jeffr-tech.livejournal.com/

Anyway, this kind of testing seems to be useful. Linux is too widely deployed 
in servers to ignore the behavior of a CPU scheduler in that scenario.

Cheers,
Alberto.