Re: [test] sched: SD-latest versus Mike's latest

Ingo Molnar
2007-04-05T19:05:40Z

* Con Kolivas <kernel@kolivas.org> wrote:

> Nice -10 on mainline ruins the latency of nice 0 tasks unlike SD. New
> scheduling class just for X? Sounds like a very complicated
> userspace-changing way to just do the equivalent of "nice -n -10"
> obfuscated.

i think you are missing the point. We _do not know in advance_ whether X
should be prioritized or not. It's the behavior of X that determines it.
When X is reniced to -10 it fixes a few corner cases, but it breaks many
other cases. We found that out time and time again.

btw., the tests i've done were not with X but using a shell prompt.

> > re-testing the weak points of SD:
> >
> > - hackbench: still unusable under such type of high load - no
> > improvement.
>
> Load of 160. Is proportional slowdown bad?

this is relative to how mainline+Mike's handles it. Users wont really
care about the why's, they'll only see the slowdown.

> > - make -j: still less interactive than Mike's - no improvement.
>
> Depends on how big your job number vs cpu is. The better the
> throttling gets with mainline the better SD gets in this comparison.
> At equal fairness mainline does not have the low latency interactivity
> SD has.

i often run make jobs with -j200 or larger, and SD gets worse than even
mainline much sooner than that.

Ingo