captures occasionally hog cpu
I have a Hauppauge WinTV PVR 150 and I'm using the ivtv drivers (version 0.3.8). After some months of trying, on and off, to track down a problem, I believe I have finally found it and it's not really a PVR 150 or IVTV problem.
The problem is that when I'm doing captures (which I normally do via: cat /dev/video > movie.mpg), from time to time, the CPU usage will shoot up to 40-50% for the process. Normally the CPU usage is under 1%. Once it goes up to 40+%, it stays there for the remainder of the capture. When this happens, the captures start dropping frames, very noticeably, probably from insufficient buffer space.
I suspected all sorts of things, driver issues, heat, etc. It now appears that the problem is disk related, and I suspect, since the drives seem to function fine otherwise, that it's actually more of a file system issue.
Captures consume a good deal of disk space, which I think is somewhere between 1 and 2 megabytes per second.
This wasn't a problem for a long time, but over time, it has become more and more of a problem. If it were Windows, I'd suspect file fragmentation as the problem and I suppose that might be happening here as well.
I'm not really sure what I can do to diagnose and fix the problem.
To diagnose it to this point, instead of doing:
cat /dev/video > movie.mpg
And I have yet to see the CPU usage go up above 1%
cat /dev/video > /dev/null
hda - 200GB - udma6
hdb - 122GB - udma6
hdc - 250GB - udma5
All 3 drives are mapped as a single logical partition:
This was the default setup that Fedora Core 3 gave me.
I don't want to repartition the drives and I'd be willing to simply stick a 4th drive in and give it its own partition if that will fix the problem for me.
But I'd like to see if I have other options (as I'm not even sure that will fix my problem). I'd certainly be interested in finding out if there's some way I can more accurately diagnose the problem.
Anyway, any help anyone could offer would be great.