On Thu, 2003-06-05 at 22:15, James Green wrote:
But when I did this fix I found that I still got overflow errors. I
instrumented the code a lot and found that the read routine couldn't keep
up with the write routine. The buffer size was the default, 8192 bytes.
This doesn't seem large enough on my PC, ie. it gets filled too quickly
before the read routine can get in. However, my PC is pretty quick, and it
is only 2% loaded, so I think the buffer default size needs increasing.
16KB was enough for me, but if somebody has a slower PC they might need
bigger. Is there any problem with making the default bigger. It's pretty
useless at the moment.
Reading this, I remember that the old drivers (ost api) for the dbox2
had a default buffer size of 256KB, which should be the reason why they
did not get as many buffer overflows as the current dvb-core drivers.
:-)
8 kBytes is sufficient to keep at least 2 sections of the theoretical
maximum size in the buffer, so it seemed to be a good default value.
Since the driver does not knows anything about the expected datarate,
it's up to the application to configure the buffer size using the
DMX_SET_BUFFER_SIZE ioctl.