Package: kdelibs-bin
Version: 4:3.4.2-3
Hi,
I've been having huge trouble doing frame grabbing from my video camera via
firewire recently. Every ~ 20 seconds a frame got dropped.
And this all despite running a -ck kernel with dvgrab running in SCHED_ISO,
which should normally avoid any and all frame drops quite easily.
Environment: P3/700 with 2.6.13-ck* kernels, CONFIG_PREEMPT and
CONFIG_PREEMPT_BKL.
I then changed to IceWM which immediately worked.
So it had to be something within the KDE environment.
A kill -STOP kded then fixed it.
Possibilities:
a) kded is doing way too much and thus stealing too much CPU. Since this should
still
never cause frame drops since dvgrab is SCHED_ISO, it would indicate a
scheduling
weakness. Highly unlikely.
b) kded calling one huge non-preemptive system call, causing huge latency during
grabbing. --> kernel issue.
c) kded calling non-preemptive system call with too high latency too often.
kded issue / kernel issue.
Note that top shows kded sometimes having 3% CPU spikes, and strace illustrates
this activity.
dvgrab has been verified to use SCHED_ISO, via schedtool.
Is there a way to improve kded to have less activity within one burst?
Other ideas?
Thanks!
Andreas Mohr
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