Log in Register FAQ Memberlist Search pcHDTV Forum Index
pcHDTV Forum

pcHDTV Forum Index -> HD-2000/3000 drivers -> kernel: dmxdev: buffer overflow
Post new topic  This topic is locked: you cannot edit posts or make replies. View previous topic :: View next topic 
kernel: dmxdev: buffer overflow
PostPosted: Sun Oct 01, 2006 11:53 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




I just started using the DVB drivers a month or two ago and now that I have the buffer overflow message turned on by default, I've discovered I'm getting lots of them It doesn't matter if I'm running X or not. Any significant system activity will cause it.

I'm using the latest v4l drivers (which I needed for the HD-2000 card to work) and I'm confused as to what the size of the buffer is. DVR_BUFFER_SIZE is hard set to 10*188*1024 in dmxdev.h, dvb_demux_open() seems to set the dvb ring buffer to a maximum of 8192 elements, then there's an ioctl called DMX_SET_BUFFER_SIZE which seems to have absolutely no effect. What do all these values have in common if anything?
View user's profile Send private message
PostPosted: Sun Oct 01, 2006 2:22 pm Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




There are two different buffers, one for the demux device and one for the dvr device. Hardly any software reads from the demux device because the api is flawed, making it nearly useless. Most software uses the dvr device. You should look at the function dvb_dvr_open().
View user's profile Send private message
PostPosted: Sun Oct 01, 2006 4:18 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Then the buffer size is fixed to DVR_BUFFER_SIZE and that ioctl to change the buffer size doesn't really do anything. I guess I'll try increasing it and see if that helps.

I was using the old ATSC dtv driver on a 2.4 kernel on a machine slower than this one for years and I really had to push the machine to cause either card to overflow. The DVB driver seems to require a lot more overhead. It improved after I increased the timeslicing to 1000HZ.
View user's profile Send private message
PostPosted: Mon Oct 02, 2006 4:53 am Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




The ioctl to change the buffer size does work, but it's for the demux buffer, not the dvr buffer. There is no ioctl to change the dvr buffer size.
View user's profile Send private message
PostPosted: Mon Oct 02, 2006 11:25 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Horray! Doubling the DVR buffer size to 20*188*1024 has eliminated the buffer overflows during general use so I at least have a way to get uncorrupted recordings. Tomorrow I'll see if I can save an uncorrupt stream while doing crazy things like removing a file or telneting to another machine.
View user's profile Send private message
kernel: dmxdev: buffer overflow
  pcHDTV Forum Index -> HD-2000/3000 drivers
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
All times are GMT - 7 Hours  
Page 1 of 1  

  
  
 Post new topic  This topic is locked: you cannot edit posts or make replies.  


Powered by phpBB © 2001-2003 phpBB Group
Theme created by Vjacheslav Trushkin