Re: [RFC][PATCH] SCHED_ISO for interactivity

Con Kolivas (
Sun, 13 Jul 2003 22:53:12 +1000

On Sun, 13 Jul 2003 20:41, Guillaume Chazarain wrote:
> Hi Con,
> I am currently testing SCHED_ISO, but I have noticed a regression:
> I do a make -j5 in linux-2.5.75/ everything is OK since gcc prio is 25.
> X and fvwm prio are 15, but when I move a window it's very jerky.

Interesting. I don't know how much smaller the timeslice can be before
different hardware will be affected. Can you report what cpu and video card
you're using? Unfortunately I don't have a range of hardware to test it on
and I chose the aggressive 1/5th timeslice size. Can you try with ISO_PENALTY
set to 2 instead?

> And btw, as I am interested in scheduler improvements, do you have a
> testcase where the stock scheduler does the bad thing? Preferably without
> KDE nor Mozilla (I don't have them installed, and I'll have access to a
> decent connection in september).

Transparency and antialiased fonts are good triggers. Launcing Xterm with
transparency has been known to cause skips. Also the obvious make -j 4 kernel
compiles, and
while true ; do a=2 ; done
as a fast onset full cpu hog

> BTW2, you all seem to test interactivity with xmms. Just for those like me
> that didn't noticed, I have just found that it skips much less with alsa's
> OSS emulation than with alsa-xmms.

Anything that increases the signal to noise ratio at helping us pick up
skips/problems is useful, but this can help those that _don't_ want skips so

> Thanks,

Thank you very much for testing and reporting.


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