[linux-dvb] Re: SkyStar-1, network code and section packing

[Johannes Stezenbach <js@convergence.de>]

Denis Fedorishenko wrote:
> Wednesday, March 10, 2004, 12:58:15 AM, you wrote:
> 
> JS> What happens with hw_sections=0 and enabled section packing?
> Huge packetloss (more 30%).
> Btw, we made another test, if i put customer on PID where is also
> another customers (overall bandwidth 3-4 Megabit/s), same effect
> (hw_sections=0):
> Section packing on - packetloss
> Without section packing - working well (even in PID, where is another
> customers have section packing turned on).

OK, with 3-4 Mbit/s on one PID you shouldn't exceed the bandwidth
limitations. Something else must go wrong.
So we've got to find out where packets are dropped.

Does ifconfig and/or 'cat /proc/net/dev' report errors?

> So maybe (but i cannot be sure), with hw_sections = 1 - it is
> impossible to use network things (this beam is overall data rate 21
> Mbit, but PID is didnt make any sense, this means even on PID
> filtering bandwidth limited?).
> But strange thing, i had look on old drivers (StartHWFilter):
...
> If there any problem, it is maybe because of another firmware? Because
> it means hw_sections is used on old drivers.

The old driver/firmware did not support software section filtering.
The bandwidth limit is in transferring data from card to PC, so
hw_sections=1 is better (filtering happens on the card), but the
downside is that the card does not do CRC check of section data.

> JS> The bandwidth of the bus between av7110 and PCI is quite limited
> JS> (I don't have exact numbers, but I think 10..15MBit/s). I guess you
> JS> are close to that limit, and some insufficient error handling
> JS> in the firmware causes the filter to stop when buffers are
> JS> filled up with hw_sections=1. It shouldn't happen with
> JS> hw_sections=0, though.
> This problem happen, even if i assign to user separate PID, and he use
> only up to 512 Kbit/s. Thats strange :(
> Another thing, again, old firmware(?) working well (except 2.6 kernel
> issues, and pc locking issue).

I suspect the reason is stricter error checking in dvb_net.
Check out dvb_net.c:dvb_net_sec() and compare the differences.

Another possibility would be a bug in the software section filter,
but I think it's rather unlikely.

> Btw. List doesnt setting correct Reply-To: ,thats not good,
> automatically reply going to person who send mail to maillist :(

This is how I want it. There's nothing worse than a private mail
accidentally going to the list.

Johannes


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