[linux-audio-user] Kernel 2.6.x latency

[Jack O'Quin]

James Stone <stone1 at btinternet.com> writes:

> On Thu, Mar 11, 2004 at 06:21:15PM +0100, Frank Barknecht wrote:

> > Another thing to check would be your X server's nice value. This used
> > to be "-10" in older Debians, but should not be set at all with 2.6. 

> How disappointing.. I just tried this, and it didn't help.. I was almost
> sure this was going to work. I am still getting many more xruns than
> with the low latency 2.4.x kernels though at least I am not getting
> xruns on opening and closing windows!
> 
> However, on doing a top in 2.6.x I noticed that quite a few processes
> are running with a nice of -10 (something called "event" among
> others..). This does not appear to be the case in 2.4.x.. perhaps this
> could be the source of the trouble.. not really sure how to fix it
> though.

This makes me wonder if there is a bug in the scheduler.  IIUC, a
realtime thread is *supposed* to have higher priority than any
non-SCHED_FIFO thread, regardless of "nice" value.  

If we can nail down a case where this is definitely happening, someone
should report it to Andrew Morton.

> I will have to stick with 2.4.25 for the time being by the looks of
> things.

You can almost certainly get better low-latency results that way, at
least for the moment.  I hope that over time 2.6.x will become just as
good.
-- 
  joq