[linux-dvb] Re: Dvb kernel w/Nebula chewing CPU time

[Clyde Stubbs <clyde@htsoft.com>]

On Thu, Nov 27, 2003 at 09:21:01AM +1100, Jamie Honan wrote:
> with bt878 the dma is always running, and scheduling the
> dvb_bt8xx_task, if there's data. If the frontend is not tuned _and_ sending

Nope, frontend is tuned (tested with MythTV and tzap) and no difference
if e.g. dvbstream is reading two PID streams from dvr0. The point is
that *some of the time* it works fine (sys CPU drops to a few %) but
I have not been able to isolate a particular sequence of steps that will
transform it from bad (high CPU usage) to good (low CPU usage).

In the low CPU usage state, I can watch live TV in Myth just fine, with
the high CPU usage state the TS gets corrupted (presumably dropped packets)
and it's unwatchable.

Detuning the front end stops the CPU usage. I assume that without a lock, the
decoder (NxT6000) stops delivering data, so the BT878 stops dma/interrupting.

I'm assuming it's some kind of bug in the dvb demux code. I'm prepared to debug
it, but just wanted to see if anyone had any good suggestions before I launch
into it.

Clyde

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Clyde Stubbs                     |            HI-TECH Software
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