Date: Fri, 19 Jan 2007 19:18:04 +0100
From: Hans Verkuil <[EMAIL PROTECTED]>
The whole buffer allocation code is crap as far as I can tell. I
completely redid the code in the current trunk version of ivtv. You
might try to include the 'max_mpg_buffers=8' module option and see if
that works. I would also recommend upgrading to the latest ivtv-0.4
version.
I tried that, and it -might- have helped, but I'm confused in the
following ways:
(a) the code (I'm running 0.4.1 on that machine, actually) seems to
indicate that max_mpg_buffers is set via a #define to 16 in
ivtv-driver.h. Why would setting it to 8 help matters?
(b) Is it max_mpg_buffers or mpg_buffers that actually determines how
much buffering is happening?
(c) There seem to be a whole bunch of MODULE_PARM_DESC's in ivtv-driver.c
that would probably be helpful in figuring out what exactly is getting
set in the driver; is there some way to get those printed? Some switch
I should set? Or do I need to recompile ivtv with something set?
[It's a little hard for me to figure out what's going on because I
-thought- I'd licked this problem a while ago, but discovered I
hadn't, and my stress-test (which forces scheduler queries, hence lots
of disk I/O) with max_mpg_buffers -seemed- to have indicated that it
was better now, but in actual usage I still saw a glitch when the
scheduler query was run, so my test seems only probablistic, hence
it's hard for me to know quickly whether something is working.]
Here's the entire contents of my /etc/modprobe.d/ivtv file at this point:
options msp3400 debug=1
options ivtv max_mpg_buffers=8 mpg_buffers=16 vbi_buffers=16
dec_osd_buffers=2
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