Multi Proc strategy

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Multi Proc strategy

Post  Ade on Tue Sep 30, 2008 9:44 pm

Thanks for organising this dedicated forum!
As we all know by now, Omnisphere is one hungry beast. Even running multiple processors is no guarantee of success as one instantiation will only address one CPU. I have just run some tests splitting a very demanding patch over two instantiations and the CPU performance meter in Nuendo dropped by around 20% (!) as the task was split over 2 of the CPUs.
I'm now resaving some of those major hog multis to take advantage of this approach.
It's a bit of a relief.... I was wondering how this thing was going to run at anything like playable latency in a real world situation.

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Re: Multi Proc strategy

Post  Casar1973 on Wed Oct 01, 2008 2:17 am

Cool information, thanks for the enlightenment Ade!

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Re: Multi Proc strategy

Post  novata on Wed Oct 01, 2008 2:28 am

I'm not so sure about the idea of running two instances. My QuadCore seems to be fully utilised when using Cubase SX3 and Omnisphere. Isn't it down to the host where multiprocessing is enabled?

I have left a link to a demo on another thread but I'll leave it here too.

OmniQuadDemo

Ade, could you possibly record your findings or post some screen grabs?
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Re: Multi Proc strategy

Post  Ade on Wed Oct 01, 2008 10:13 am

I'll definitely post some figures. I believe that it is the plugin itself which must be multi proc aware. Nuendo, which shares the same engine as Cubase, is certainly loading only one CPU per instance of Omni. It's worth finding out if there are differences between DAWs in this respect.

BTW - can't view your AVI on my internet Mac.

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Re: Multi Proc strategy

Post  Ade on Wed Oct 01, 2008 5:28 pm

Here you can see an the results of an Omnisphere Multi played in one instantiation. As you can see, only the first CPU is being addressed and the VST meter is hovering around 45%.



Here's the identical patch split over two Omnispheres.
CPUs 1 and 3 are predominantly being hit - at about half the load that one Omni was requiring. That means each CPU has more headroom and is less likely to click and pop....
and look at the VST meter! There is just under 20% difference for the same audio result.
(There is a little flickering on those meters that the pics did not get... it's safe to say between 15-20% is saved.)
I'm a little nonplussed as to why CPUs 2 and 4 gain a little more activity with two instantiations. CPUs 2 thru 4 stayed fairly dormant with one instantiation. Regardless, the overall affect is that my system is more stable with the load spread... and I can only do that with more than one Omni. Is anyone able to demonstrate loading of multiple CPUs with one Omnisphere?

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Re: Multi Proc strategy

Post  orbital on Wed Oct 01, 2008 11:12 pm

Greetings!

Just picked mine up today. I'm using Nuendo 4 on a Macbook Pro. ASIO hit in Nuendo when a multi is loaded sits quite low I was surprised to see. Just my $.02

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Re: Multi Proc strategy

Post  Ade on Thu Oct 02, 2008 12:06 am

Any specific patch? What buffer setting?

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Re: Multi Proc strategy

Post  novata on Thu Oct 02, 2008 1:22 am

Now here's an odd thing. In Cubase SX3 I was hitting all four cores, but with Xlutop Chainer as a host on it's own I'm only hitting one core with Omni. It seems to be host dependent.

I've got issues with my sound card at the moment. Audiophile 2496 keeps dying. Aghhh

I was going to do some more tests because I don't think I should be hitting all four cores as hard as I do in Cubase. There is definatley something wrong.
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Re: Multi Proc strategy

Post  Pi_314 on Thu Oct 02, 2008 4:26 pm

Core management is something left up to the host entirely. Cubase SX3 and Cubase 4 handle the cores differently, and in my opinion, they both handle it badly. Pops and clicks are happening regardless of whether one core is used, or all from what I can tell. At the moment it looks like a multicore gets you nowhere with the Omni beast. It could be two years or more, before you can expect smooth sailing with Omnisphere.

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Re: Multi Proc strategy

Post  Hans Scheffler on Fri Oct 03, 2008 1:41 am

on my 8core Macpro i get a much better performance when i open up several instances of Omnisphere with just one or two patches in each.
I can see that Logic starts distributing the tasks to several cores in that case as opposed to having one core do all the work if all the patches reside in a single instance.
On the downside opening several instances uses a bit more RAM.

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Re: Multi Proc strategy

Post  Ade on Fri Oct 03, 2008 12:51 pm

novata wrote:It seems to be host dependent.

It's not surprising that Chainer is not multi-core compliant. It's getting pretty long in the tooth. The fact that Cubase can turn off MCP indicates that the host must be up to the task.... but it's possible that the plugin must also be coded appropriately... and only Eric and Co. know the answer to that. And it's also been demonstrated on this thread that some people are able to spread the load when one one instance of Omni is running. That points to the CPUs/MBs too!
It's looking like a bit of a mine field... and obviously my original post can't be viewed as reliable information for all users. Embarassed confused

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intel core duo, too many patches, gets clicking

Post  wired on Sun Mar 22, 2009 2:42 pm

i loaded 2 or 3 guitars at 8 voice, and ya, lots of clicking, i think you can only get one going to be safe, or turn off the effects and stuff, ...to bad tho, the way i used multi was just using different midi channels instead of layering, don't know if that can hurt midi perf. or not

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Re: Multi Proc strategy

Post  darren on Sat Apr 04, 2009 10:08 am

i really don't think that a host can "force" a singe VSTi to use more than one core. i have had conversations with one of the lead devs on a DAW i use and he said that it was impossible to split one instance of a VSTi over more than one core. i'm inclined to believe him.

i'm on a quad core 2.4 GHz Intel box, and I often run one instance of Omni with 4-8 patches and I find that the CPU usage is pretty acceptable, but with any VSTi I have to run my ProFire 2626 audio interface at a very high buffer. This isn't a big deal for me since I usually do all of the synth work before I get around to recording anything live and by that point I've frozen tracks. And of course, Omni doesn't seem to use much/any CPU when not making sound.

i also have a dual core 1.3GHz laptop and Omni definitely has challenges but even that limps along when i have no other option.

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Re: Multi Proc strategy

Post  Fretpick on Sun Jun 14, 2009 5:53 pm

I have a Q9450 & I'm waiting to see how Omni runs on that. I'm not worried though as the program can be tailored.
cheers
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