Re: [linux-audio-user] Kernel 2.6.x latency - Linux-audio-user

11 Mar 2004

Hi,

Has anyone tried the different IO schedulers with 2.6? I've seen some 
systems that feel much more responsive with the non-default Deadline 
scheduler than the default anticipatory scheduler .. I haven't done any 
audio specific latency tests though.

later,
Steve

Jack O'Quin wrote:
...
  James Stone &lt;stone1(a)btinternet.com&gt; 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. 