In [c] and [d] I'm applying an additional latency patch to the
drm
kernel driver that affects radeon, r128 and mga based cards. The patch
is old and _illegal_ as it does reschedules with a lock on. So far the
computer has not locked up but I guess it is a matter of time :-)
can you send me that patch (or point at an URL) ?
A real test with the Jack low latency server reveals that something
else
is creating latency hits.
do you run Jack as realtime process ??
So, latencytest is happy but a real test with real applications is
not.
it might be an application artifact/interaction
Other important data points:
- xruns seem to be related to graphics activity
- booting FC2 into 2.4.26 with the low latency and preempt patches gives
me similar results (latency hits when running jack and jack apps)
- booting FC1 into 2.4.26 (same hardware, just replace the hard disk)
gives me a rock solid system (no xruns whatsoever, down to 128x2).
So, it would seem to me that it is not (only) the kernel..........
Things I could not make work:
- testing 2.6.6-1.391.x in FC1. For some reason init does not get
executed, probably a library problem somewhere...
you need to pass vdso=0 to the kernel there.
Any ideas on what could cause this????
try disabling DRI.
DRI sometimes can "hold" the pci bus for quite some time, which by
definition causes latency since no IO can be done