title: How to query the available data size in Linux DVB kernel demux buffers?
body: <p>I am using a Linux-DVB frontend/demux driver pair to get a program stream remuxed from live broadcast TS into user land. I am using the poll/read combination, however, to keep the context switching and kernel to user space copying penalties at minimum, I only want to read data if it is bigger than a certain size.</p>
  
  <p>I couldn't find any way to query the available data size in the demux buffers nor any option to specify the poll notify size.</p>
  
  <p>Is anybody aware of any such functionality? If not, is it unreasonable to have such a feature request on the DVB api?</p>
  
  <p>Regards,</p>