[linux-dvb] DVB cards in a Server, Buffer sizes

[Ralph Metzler <rjkm@metzlerbros.de>]

Juergen Pfennig writes:
 > bool ZTuning::setDemux(HANDLE dmxfd, bool bAudio, bool bDvr)
 > {
 >  if(bDvr) {
 >   int buffersize = 64 * 1024;
 >   if (ioctl(dmxfd, DMX_SET_BUFFER_SIZE, buffersize) == -1) {
 >    ZZapDvb::printError("DVB setup (ioctl DMX_SET_BUFFER_SIZE) failed:");
 >    return false;
 >   }
 >  }
 >  ....bla bla bla...
 > }
 > 
 > As you can see the s/t/c-zap family of programs sets a buffer size of 64kByte 
 > on the demux device. This is not very much. Even a workstation can be 
 > (disk-io) busy for a few seconds - not to mention a server. I do not want to 
 > discuss the problem of missing (disk-)io priorities in the kernel, but my 
 > question simply is:
 > 
 >     IS IT RECOMMENDED AND SAFE TO USE A LARGER BUFFER?
 > 
 > I would feel better to tell the driver to grab 512 kByte of precious kernel 
 > memory. What do you think?


Considering how this ioctl is currently implemented for the dvr device 
this question is kind of moot. 


Ralph