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[vdr] Re: Ring buffer overflows - system too slow?



Oliver Endriss wrote:
Wolfgang Fritz wrote:

I am running VDR with one Nexus-s rev. 2.2 on a 133 MHz/64MB Pentium
board with Kernel 2.4.20, newest CVS DVB driver and VDR-1.1.21

If I compile VDR with

#define DO_REC_AND_PLAY_ON_PRIMARY_DEVICE 1
#define DO_MULTIPLE_RECORDINGS 1

I get lots of "ring buffer overflow" messages while recording and the
recording is damaged.

This happens
- Sometimes during recording alone
- Often when recording while replaying another recording or time
shift

The strange thing is that sometimes a recording + replay is working
stable with system load at abt 0.6 to 0.8 and on the next try I get
the ringbuffer messages and the load rises to 1.2 - 1.5.

It depends on the data rate. For example, if the picture contents change rapidly, there is more data to be processed and your machine reaches its limit.


Could be. But I also saw it on the same transponder/station/programme:
Recording 1: bad, stopped rec. 1, started rec. 2 immediately after that: OK, stopped rec. 2, started rec 3: bad again.

Maybe my system is simply to slow? Has anyone out there a single
DVB-s setup working reliable with DO_REC_AND_PLAY_ON_PRIMARY_DEVICE
etc. enabled and if so, on what kind of hardware?

I'm using a PI-233 MHz. During recording, system load varies between 20 and 100%. Probably this is too much for your P-133.

I think the situation could be improved if parts of the driver would be optimized. In time-shift mode the driver wastes lots of CPU cycles busy-waiting in wait_for_debi_done(). If this could be changed,
CPU utilization of the driver would be reduced significantly.
I wish I had more time to work on this. Because there is no documentation
about the driver-arm-communication this is a quite time-consuming task.

It's a pity the ARM code is not open.

Thank you,

Wolfgang
Oliver





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