[linux-dvb] Re: Reading in 188 byte chunks?

[Johannes Stezenbach <js@linuxtv.org>]

Josef Wolf wrote:
> The API-documentation says that reading from /dev/dvb/adapterX/dvrY is to

Where exactly do the docs say that? Because if they are wrong and
must be corrected.

> be done in 188 byte chunks.  On an average stream (4Mbps), this results in 
> about 2660 system calls per second.  Receiving a whole transponder with
> 27.5Msym/s (that is 55Mbps) results in 36570 syscalls per second.  Since
> syscalls are expensive operations, this seems to be a pretty big overhead
> to me.
> 
> Is there any reason _not_ to return all available packets?  I'd pretty
> much prefer to read(dvrfd,buf,188*100) (in nonblocking mode) and get
> all available packets in just one call.

The API does not support reading partial TS packets, however
you can read as many packets in one go as you like.

Johannes