Multi CPU/Core Load With Amplitube VST

system wxp 32 , 4gigram, q6600@4x3ghz

if i add some amplitubes on some severall channels one core gets to his 100% limit. the other 3 cores are almost without load, 2 cores are empty and one is loaded with about 20%.

it happens with amplitube 1.1.1 with a selfmade preset.
use of multicpu for plugin is activated.

have you checked if this happens only in Renoise? Amplitube 1 is a very old plugin so it’s likely to not be multicore capable; in such case there is nothing Renoise can do to divide the load of one instance on several CPU’s

Are all CPUs enabled in renoises audio preferences? How does this songs routing look like? Do you feed all tracks in one send track?

Also do you get a real performance problem, or just wonder why your task manager shows that one core is fully used while the others are idling? We don’t force the system to use this or that CPU for this or that track. All we do is giving the system the possibility to do so. On low working loads it may use one core more than the the others…

Which CPU usage do you get in Renoise with one core enabled vs all cores enabled? Thats what interests you.

i only can test this in renoise.
i doesnt expect that amplitude with one instance uses more cores, but i really can expect that every instance of amplitude get a core by the host aplication, i think?

3 enabled

every track have his own amplitude and get together in one sendtrack, this sendtrack then goes direct to master.

no, and without the second amplitude plugin the load of the cores are very low, about 10-20 %. so its not a problem of the song or jhis structure.

i got massive audio-cracklings / distortion and the cpu-load threshold message.

with 3 cores enabled
4 x 12-24 %

i currently tested to get more load with a nuew amplitude vst in a track but nothing happened, no more load, no cpu-treshold warning, nothing ^^

with 1 cores enabled
1 x 26%

I mean the CPU usage in Renoise, not in the taskmanager, but if you get crackles at such low CPU loads, then you should increase your Audio latency - ASIO buffer size. Usually one gets such crackles when DSPs use temporarily high working loads, create CPU spikes. Even 10 cores will not help in such cases. At which latency are you currently working?

I’m not sure what you mean here.

But the higher the latency, the more individual tracks you have, the better the working load will be balanced. It can never be perfectly shared between all cores. Plugins and thus the track do not constantly use the same amount of CPU, the system also does stuff in the background - uses the core. Renoises GUI also needs some CPU from time to time and its not that 2 more cores mean 2x more performance. I know you just have a problem that you want to be “solved” somehow, so please try what I suggested above: using a bigger latency to get rid of the crackles at such low working loads…

taktik, you probably overlooked this sentence: if I don’t fail, in such a scenario all the 3 instances are managed on a single core anyway?

No, we do calc the send together with the master in the “main core” then, but only if the overhead thats added by this way of routing makes something faster…

But hey, do we really have to go that deep into the technical details?

pvcf got some crackles in a song and wondered why. OK, lets help him to solve this, instead of discussing this topic at such a detailed level to death.

Renoise magically uses multiple cores of your CPU and tries to do the best out of it, depending on your current songs routing, soundcard settings & stuff. But you NEVER will get a perfectly balanced load.

i have setted 128 (2.9msec) delay, its a dsp2000 card, hoontech, now esi.

not some qrackles, its a complete channeldistortion with audioengine stopping (threshold is 96%/500ms ).

please give some hints about optimal track/routing configuration for best mulitcore support, that would help 8)

okay; i have managed to found the bug:
i have
stormdrummsINS2 (which is a alias if stormdrummsINS1 but with same midichannel, both # 01)

i played in (multi)track1 a drummkid with stormdrummsINS1, in (multi)track2 i played some stormdrummsINS1 AND mixed between stormdrummsINS2 AND a sample which is triggered by renoise itself.
this crashed the audio tracks of this two channels (but without cpu-load-message, this comes than later if 2 amplutubes are together in one subtrack).