[SDL] Re: SDL_mixer & dual CPU starvation problem

[Tom Gilbert]

Hi there,

I'm happy to report that this was *not* a problem with SDL.

Having upgraded the system to a new kernel [2.4.0-test9],
DRI CVS XFree86 4 and an AGP G400 the problem has gone away.

NVIDIAs driver FAQ contains a note to SMP users - must use
binutils >= 2.9.5 otherwise kernel spinlocks don't work right.
Perhaps that's what was going on - at any rate, nothing to do 
with SDL.

thanks,

Tom Gilbert
http://www.AlteredWorlds.com

Tom Gilbert wrote:
> 
> Hi Guys,
> 
> Just noticed an odd problem with the following combination:
> DUAL PentiumII 300 box
> SDL-1.1.4
> SDL_mixer-1.0.6
> smpeg-0.4.0
> linux 2.2.15 and linux 2.2.17
> 
> AlteredSaver on Linux uses the above libraries to play sounds.
> Everything works well enough on a single CPU box, but when I try running
> on a dual CPU machine, the application startup process is rather messed
> up.
> 
> NORMAL CASE:
> ============
> W/o sound enabled, or on a single CPU box with sound, the app starts in
> around 3 seconds.
> 
> PROBLEM CASE:
> =============
> On a dual CPU box with sound enabled in saver settings, app. takes more
> than 10 seconds, and you sometimes hear a couple of sections of the
> music track as follows: after some time, a second long burst of sound,
> then a gap, then another second of sound, then finally the whole thing
> starts playing correctly.
> 
> If I use the AlteredSaver settings to launch plaympeg on the music track
> as an 'external helper' (commercial version only) , everything works
> fine - in this case, I am 'execvp'ing plaympeg myself rather than
> letting SDL_mixer do it.
> 
> SO - looks like there might be some problem with the locking code in
> SDL_mixer? If I boot the dual machine using a single CPU kernel, it
> works fine.
> 
> QUESTION:
> =========
> Is this a known issue? If not, what can I do to help?
> 
> Problem can be seen with free version of AlteredSaver at:
> http://www.AlteredWorlds.com/linux/altered-2.3-full.tgz [15MB]
> 
> thanks,
> 
> Tom Gilbert
> http://www.AlteredWorlds.com