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Re: [sc-users] Raspberry Pi 3 - server crashes above 65% CPU



hi,
it sounds a bit strange that the server crashes at around 65%.  in my experience one can go higher and when overload you normally start hearing dropouts and crackles (xruns). the server can even take that for a while and recover if the load decreases.  seldom does the server totally crash.  i think sclang and jack more often locks up first.

i'd try to figure this out by writing a synthdef that eats a lot of cpu (a static one - not spawning many new synths from sclang).  leave it running for a while and then add another one.  how high can you go in server cpu?
do you get roughly the same performance when using the pi's internal audio vs the external usb card?

if you can push you test synthdef much higher and up toward 100% with both audio cards then it's more likely a problem with your sc code.  are you passing a lot of data between sclang and scsynth?  network clogged up?
or doing something that eats up ram?  (did you minimise gpu memory to give a bit more ram to the cpu under raspi-config -> advanced?)

overheating can be ruled out by temporarily adding a spare computer fan blowing over the board and see if it takes longer time until crash.  heatsinks might help but i doubt this a heat issue if it is only sc crashing.  also try with another power supply and other usb cables.  bad usb cables / supplies can cause a voltage drop and then the system might crash/glitch or power to external usb devices drop when the pi itself is drawing a lot of current.

sorry, don't know if supernova could help or if it is at all possible to install on a pi.
good luck,
_f

> 10 jan. 2018 kl. 22:10 skrev mott@xxxxxxxxxx:
> 
> Hello list,
> 
> I'm doing some experiments running a project on a Raspberry Pi 3, for which I built SC from source using the instructions here: http://supercollider.github.io/development/building-raspberrypi
> 
> It's running OK, however once the CPU rises above 65% capacity, the server crashes and scsynth needs to be killed off before the code can be run again. There are usually no error messages. Sometimes the following is printed before the crash:
> 
> JackEngine::XRun: client = SuperCollider was not finished, state = Running
> JackAudioDriver::ProcessGraphAsyncMaster: Process error
> 
> And after the crash, the command: s.avgCPU  yields a static result, so I assume that it is the server that has crashed.
> 
> Firstly, is this to be expected?
> 
> The CPU is set to "performance" mode and I'm running the code from the command line, without scide/emacs. The jack set up is:
> 
> /usr/local/bin/jackd -P75 -dalsa -dhw:1 -r44100 -p1024 -n3
> 
> This has as large a latency as I'd wish to use on this particular project. Sometimes I can run a program for hours at -p1024, other times, for no apparent reason I need to put 2048 to run something a bit heavy. Temperature of the board?
> 
> At the moment I'm using a Behringer UCA222 USB interface. Without a powered hub the server crashed at around 35 or 45%. I have an stereo "injector sound card" on order. This sits right on the board and doesn't require additional power. It capable of very low latencies apparently and I hope it will help.
> 
> The other question I wanted to ask is, might supernova be solution? It didn't get built with the instructions cited above, so I don't know if it can be run on a Raspi 3. Using the "nmon" utility, I see that SC is using only one of the 4 cores.
> 
> I'd be grateful for any suggestions you can send.
> 
> All the best!
> 
> Iain
> 
> -- 
> _________
> Iain Mott
> http://escuta.org
> 
> 
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