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[linux-dvb] Quality of dvb-kernel in upcoming 2.6



HI All

To get a glance of new software, I upgraded my debian
woody into upcomaing sarge (currently also named 'testing')
and compiled latest kenel 2.6.0-test7 and applied patches
(actually one patch from dvb-kernel 01-xx-something.
another patch 03-xx-something failed).

Well, compared to same dvb-kernel on 2.4 some things 
related to dvb-s are inmproved, while some things related
to budget are broken.

Improved
--------
if the frontend module is removed while the
frontend is being used, the fronted process gets just
a segfault and this removal no longer crashes the machine.
Kudos to frontend people

Also the work-queue for av7110 (hopefully) solves the 
crash issue when changing a lot the dvb-s filters 
(zapping much and often). That was the greatest problem
of dvb-s, Well done too!


Broken
------
Budget and network.

I tested budget on my budget-patch card, but I think it should
manifest on other budgets as well. So:

On budget, mplayer can be used to watch some video transmission 
but it seriously looses packets and skips frames.

On network at dvb-s, some packets seem to creep in now and then,
it could be good for ping-ing somehost and doing few telnets
but definitely far from the whole bandwidth. 
(OK, on 2.4 is mostly the same thing and we know why)

Moreover, if the dvb-ttpci is removed while network interface is
active, the interface is not removed together with the driver and
kernel will crash soon after. (On 2.4 network interfaces used to
gracefully go away when the driver is removed)

On network at budget, network doesn't work at all. I haven't received a
single packet with it. (while on 2.4 it works much better,
while also not perfect, getting about 90% of full bandwidth)

The mysterious packet loss can be seen with e.g. ethereal when the
whole bandwidth is captured and then attempted to follow. (click on
some tcp entry and select "Time-sequence graph (Stevens)"
On X axis is time, on Y axis is byte offset. Discontinuities on
Y axis. Packet loss denote vertical jumps or missing vertical dots 
on the graph. Here I enclose 2 png's of ethereal, one having
no packet loss and the other I draw red arrows at some packet loss 
points, you could spot more...

Emard

Attachment: no_packet_loss.png
Description: PNG image

Attachment: packetloss.png
Description: PNG image


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