Re: [PATCH] Preemption Latency Measurement Tool

Dieter Nützel
2001-09-23T00:42:26Z

Am Sonntag, 23. September 2001 02:15 schrieb safemode:
> On Saturday 22 September 2001 19:46, Dieter Nützel wrote:
> > Am Sonntag, 23. September 2001 01:40 schrieb safemode:
> > > ok. The preemption patch helps realtime applications in linux be a
> > > little more close to realtime. I understand that. But your mp3 player
> > > shouldn't need root permission or renicing or realtime priority flags
> > > to play mp3s. To test how well the latency patches are working you
> > > should be running things all at the same priority. The main issue
> > > people are having with skipping mp3s is not in the decoding of the mp3
> > > or in the retrieving of the file, it's in the playing in the soundcard.
> > > That's being affected by dbench flooding the system with irq requests.
> > > I'm inclined to believe it's irq requests because the _only_ time i
> > > have problems with mp3s (and i dont change priority levels) is when A.
> > > i do a cdparanoia -Z -B "1-" or dbench 32. I bet if someone did
> > > these tests on scsi hardware with the latency patch, they'd find much
> > > better results than us users of ide devices.
> >
> > Nope.
> > If you would have read (all) posts about this and related threads you
> > should have noticed that I am and others running SCSI systems...
>
> hrmm strange because the only thing that could be causing the soundcard to
> skip would be irq requests still stuck in the cpu as far as i know. I only
> get that with massive ide access and that's it. Also that is when linux is
> juggling them all equally.
>
> > > even i dont get any skips when i run the player at nice -n -20.
> >
> > During dbench 16/32 and higher? Are you sure?
>
> I ran it myself and i dont drink alcohol or take drugs. so yea, i'm sure
> :)

:-)))

I would only to be sure. 'cause I get this regularly.

> If i went high enough i suppose the same problem would occur. it's
> probably in an area of the kernel where the preempt patch doesn't work
> (yet). It does happen on cdparanoia -Z -B "1"

I am under the impression that we didn't found the cause of it, yet.

> I dont think anything ide is safe from that.

No comment on this...:-)

So, do you running ReiserFS or what?

Thanks,
Dieter