[linux-audio-dev] [REQUEST] test the influence of linux1394 kernel drivers on scheduling latency

[Pieter Palmers]

Hi all,

This weekend I've discovered a (serious) kernel scheduling latency issue 
with the current ieee1394 kernel drivers. Before I submit something 
about this to lkml, I'd like some more tests. I've been able to 
reproduce this on two different machines, so I suspect that this is a 
more general problem.

The problem summary is that running ieee1394 ISO traffic can cause 
scheduling latency spikes up to 1ms, even for RT threads with higher 
priority.

I've written a simple test suite that can be used to reproduce this 
behavior. The only thing needed is a firewire host controller (no 
firewire devices). I'd appreciate it if some people would try the test 
so that I can have an overview of the problem. Of course, this applies 
mostly to people running an -RT patched kernel.

You can find the test suite here: 
http://freebob.sourceforge.net/old/ieee1394-latencytest.tar.gz
see the README for details.

Please report the maximum latency you get and the kernel/hardware you're 
running.

Many thanks,

Pieter Palmers
FreeBoB developer