[vdr] Re: [PATCH] real time scheduling for vdr-1.2.6pre3

[Andreas Schultz <aschultz@warp10.net>]

Hi Frederick,

On Sunday 02 November 2003 4:34 pm, Frederick Page wrote:
> Hi Andreas,
>
> Andreas Schultz wrote on Sun, Nov 02 2003:
> >A patch that lets vdr threads run at real time scheduling priorities
>
> I e.g. have all background jobs (commercial scans, convert/transcode
> to other formats, etc.) running at "nice -n 19" or "at -q Z" and
> absolutely no problems (at least none that I'm aware of) with vdr at
> normal priority.
>
> So (please don't take it as criticism) I wonder, why one would need to
> run vdr at high priorities?

Well, this patch started as an experiment to solve some playback problems i 
had with the DVD stuff. It turned out that it didn't help (much). However, I 
have found that running vdr at realtime priorities makes several things 
"smoother" for me, e.g.:
- response to RCU keys appears to be faster
- the entiere OSD appears to be snapier
- background jobs with extrem I/O activity do no longer impact vdr 
   (cd /usr/src/linux; make -j3 ;-))

The patch should also highlight race conditions and deadlooks due to the more 
stringent requirements for realtime. For example, lock at the changes in 
dvbplayer.c, this basicly was a very tight busy loop execute under a lock, 
not a good thing(tm).

Have fun

Andreas



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