Does multicore support really work (well)?

dreamtribe · Post by **dreamtribe** » Sun Apr 27, 2008 8:02 pm

Hi,

I just purchased a new Mac Pro 8-core to run Ableton Live. I was so excited to get this baby in the studio to see how much extra horsepower I might gather over my old systems. Mostly, I was hoping that Live would distribute Audio Unit plug-in instruments over all cores. Does Live do this?

In my first test, I used Native Instruments Reaktor (5.1.5.002). Reaktor shows the ensemble using 10% (approx) of CPU and Live shows the same. If I run this same ensemble in Logic, Reaktor shows 10% but Live shows 10% ONLY one ONE CORE of the 8!

I have multicore support turned on in prefs and I'm running Live 7.0.5.

Can anyone help with a clear understanding of how Live handles multicore?

Thanks,

Charley

Lux Libra · Post by **Lux Libra** » Sun Apr 27, 2008 8:34 pm

Live's way of using multiprocessors is to address the cpus trackwise.
1st Track CPU1
2ndTrack CPU2
etc.

that means one track can't use more than 1 cpu.......so, a reaktor ensemble
can sure hit 10 % on ONE cpu (Live's cpu meter don't show you detailed cpu load, just the average).

sparklepuff · Post by **sparklepuff** » Sun Apr 27, 2008 8:48 pm

Live's CPU meter is wack. Open up your Activity Monitor to look at what's actually happening.

keithwired · Post by **keithwired** » Sun Apr 27, 2008 9:07 pm

yea ctrl + alt + delete and look at the individual graphs for each core, since you have 8 cores each track is going to be assigned to one core which gives you A LOT of processing power since each track is being handled by its own processor. I hope you have at least 4 gigs of ram if not more. I generally like to have at least a gig of ram per core.

sparklepuff · Post by **sparklepuff** » Sun Apr 27, 2008 9:51 pm

keithwired wrote:yea ctrl + alt + delete...

That doesn't do anything on a Mac.

Olga · Post by **Olga** » Sun Apr 27, 2008 10:14 pm

m:o wrote:Live's way of using multiprocessors is to address the cpus trackwise.
1st Track CPU1
2ndTrack CPU2
etc.

that means one track can't use more than 1 cpu.......so, a reaktor ensemble
can sure hit 10 % on ONE cpu (Live's cpu meter don't show you detailed cpu load, just the average).

Ok how about this. If the only track you have open is track #1 with Drum Rack on it filled with 50 samples with plugins all over the place inside that drum rack does that mean that the other 7 cores are going to be doing nothing for Live at that point? If so, what a waste.

Lux Libra · Post by **Lux Libra** » Sun Apr 27, 2008 10:21 pm

Olga wrote:
m:o wrote:Live's way of using multiprocessors is to address the cpus trackwise.
1st Track CPU1
2ndTrack CPU2
etc.

that means one track can't use more than 1 cpu.......so, a reaktor ensemble
can sure hit 10 % on ONE cpu (Live's cpu meter don't show you detailed cpu load, just the average).

Ok how about this. If the only track you have open is track #1 with Drum Rack on it filled with 50 samples with plugins all over the place inside that drum rack does that mean that the other 7 cores are going to be doing nothing for Live at that point? If so, what a waste.

Yes, they're not processing that track. I don't know how general programm
things are processed. maybe they get distributed on all cores ?
In reallife, the Multiprocessor handling works damn well for me on a quad.

ewistrand · Post by **ewistrand** » Sun Apr 27, 2008 10:36 pm

Your plugins themselves won't multithread (with the exception of some of the large samplers/sample players)- they aren't designed to. What the host will do is either alternate plugin instances or tracks between cores, depending on the host's multithreading scheme.

ew

Olga · Post by **Olga** » Mon Apr 28, 2008 12:28 am

ewistrand wrote: What the host will do is either alternate plugin instances or tracks between cores, depending on the host's multithreading scheme.

ew

I'm really trying to figure this out as I was about to get an 8 core 2.8ghz Mac pro w/ 8GB Ram. I program live 7 using the drum rack like an MPC 4000 loaded with drums and other samples so basically all midi on that channel. So I guess the bottom line of what I'm asking is, when you load sound after sound into drum rack and drum rack creates a new 'track' for each sound within drum rack, do those count as separate tracks as seen by the cores? Or does live default it all to that one instance of drum rack? Confusing, sorry. drum rack multiple tracks within a track. But thanks for any reply if you or anyone knows. Otherwise I'll just opt for the 4 core.

hacktheplanet · Post by **hacktheplanet** » Mon Apr 28, 2008 1:16 am

All I know is when I bought the multicore support version (5.22 iirc), performance improved dramatically.