SCHED_ULE & niceness / rtprio

韓家標 Bill Hacker askbill at
Wed Nov 21 01:30:04 PST 2007

Michal Varga wrote:
> On Tue, 2007-11-20 at 14:08 -1000, Jeff Roberson wrote:
>> I definitely knew about problems with positively niced tasks.  I had not 
>> heard about the negative nice problems.  This is my top priority as far as 
>> opensource goes.  I've been unfortunately busy with other things however. 
>> I hope to get to this soon.
>> Thanks,
>> Jeff
> Just for the record, I have one user here claiming the same symptoms.
> His description exactly matches that of Yar Tikhiy, sound popping when
> switching windows in Gnome, clicking url in browser, etc. But there are
> few diferences:
> - Switching ULE for 4BSD does nothing for him, he says the sound
> jerkiness is still there, unchanged.
> - He didn't play manually with any particular niceness, everything
> running in default priorities. I let him test sound in totem, audacious
> (with various buffer sizes), then mplayer from console, without GUI.. No
> difference, sound pausing in every one.
> Another problem I see is that he is using the *exact* custom built and
> tuned FreeBSD configuration that I've deployed on a number of other
> machines and I just can't replicate any of the symptoms. From and old
> Pentium 3, through x86 Athlons, dual core AMD64 (with either smp or up
> kernel), some sort of Sempron+nforce3 - there is no single other place
> I'm aware of that this happens, only this particular guys hardware.
> Did you guys with the symptoms tried to cross-check your hardware lists
> to see if you don't have something in common?
> m.
Here's something that *should* be unrelated, yet may shed some light..

OS X 10.3.9, not 'real *BSD, 1 GHz G4 1 GB RAM, video/audio playback in Flash, 
ordinarily smooth as silk, goes choppy when there is nought but the browser  - 
and several ssh sessions running... Suspicion is the encryption workload of the 
ssh sessions, which are tailing -f the varnishd log, MTA logs, etc. of several 
servers. Very easily reproduced.

Will try a comparison tonight in FreeBSD, as much as it pains me to even support 
such 'candy' on my headless server OS of choice ...


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