[mythtv-users] mythbackend

[Aran Cox]

Your machine should probably not crash.  I use linux in a variety of
situations including where the CPU is pegged out for long stretches. 
This is the situation when you play any modern 3d game (or most games
really.)  If your machine is crashing, you should probably look into why
that is first!  See if you can crash it without using mythtv... 

Linux generally uses all available RAM, all the time.  Any RAM not used
by processes gets used for cache.  It's normal to have very little RAM
free at any one time.

The size of the processes can be very misleading as well.  For one, the
RSS (resident) size of the process is what's actually in memory.  Also,
you might notice that there are a large number of shared pages as well. 
This means that those pages of memory are also used by another program,
quite likely other instances of the same program but I believe it
includes shared libraries as well.

I wouldn't worry so much about seeing multiple processes, perhaps
someone more knowledgeable about the code could comment on that.

What happens with LiveTV (or playing back a recording which is not
finished) is that all the AV data goes over a tcp socket instead of
mythfrontend reading directly from the unfinished file.  This actually
takes a healthy amount of CPU time for mythbackend to handle (it seems
to me like too much, but what do I know.)  My 1400 MHz athlon was in the
same boat... I could record 2 shows, and playback a previously recorded
show but if I tried playing a show still recording (while recording
another) or using livetv (again while recording another) I would get
very choppy playback.  

In any case, it seems like you're system is simply borderline fast
enough and you should either up your hardware or look into making sure
everything is set up correctly.

DMA enabled on all hard drives (and probably CD-ROMS too)?
Xvideo extensions work for your card?
Try seeing if IRQ's are shared for critical devices (like the capture
card and your video card) and if they are split them up.

All of the above and many other things may make the difference in
getting your system running smoothly.  

Hope that helps...

PS:  Almost everything I've said here has been said more clearly before
on this list... the archives are your friend.



On Thu, 2003-05-22 at 16:09, Hellboy wrote:
> I noticed when I was running MythTV, and watching Live TV that my CPU
> utilization was through the roof. My Athlon 900 was running between 88% and
> 94.8% and leaving me with about 8MB of RAM left out of 384MB. Needless to
> say, that the box crashes for what I'm assuming is too heavy of a workload.
> I used SSH to log in remotely, and noticed that there were between 4 and 6
> processes for mythbackend that were running. Also, there were 2 or 3
> instances of mythfrontend running as well, each taking up 33MB of RAM. The
> number would fluctuate (one minute there would be two processes, the next
> would be six, then back again).
> According to the docs, an 800MHZ P3 should be able to encode and decode
> allowing for Live TV  watching (although I'm assuming not much else). I
> realize my CPU specs are not much higher than the bare minimum, and my RAM
> is lower than the 512MB but it looks like it should be able to pull it off.
> I'm using RTJPEG at the default cap res also.
> What concerns me is the multiple instances of both programs running, and I'm
> wondering if this normal, or if it is something I could pare back on. Sorry
> if this is kind of a noob question, but, well, I'm kind of a noob at this.
> Thanks for the help.
> 
> Wes
> 
> P.S. Down with SCO!!
> 
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