Multiple Cores

[True North]

Multi-core based machines are now a major factor pushing forward the viability of natively run DAW's such as Reaper and many others.

There was a fairly extensive thread in the Steinberg Nuendo forum which outlined some issues with Steiny DAW's properly managing multiple cores. The problem was somewhat masked with four cores but seemed to be highlighted with the introduction of Dual - Quads. The problem was most noticable when latencies dipped at and below 64 samples. For some reason the single Quads outperformed the Dual Quads - Steiny later came out and admitted that there were issues with the way their managed multiple cores.

http://www.nuendo.com/phpbb2/viewtop...317&highlight=

So many of the major DAW's have come out stating that they are multi-core ready but this technology is all so new I am wondering if the issues are only Steinbergs. When you couple the 'newness' of the technology with the fact that the two majors (Intel and AMD) have different CPU architectures I wonder if it is possible to make a blanket statement that your DAW (any DAW) is multi-core ready.

From a programming standpoint, is it a fairly simple task to make a DAW like Reaper multi-core ready?

Can DAW companies truthfully make blanket statements like Multi Core ready ?

Are there different considerations in programming for managing multi cores with AMD VS Intel chips?

Is there any forseeable issues in moving from 8 cores to lets say 16 cores ?

Thanks.

[Justin Frankel]

Originally Posted by True North

Multi-core based machines are now a major factor pushing forward the viability of natively run DAW's such as Reaper and many others.

There was a fairly extensive thread in the Steinberg Nuendo forum which outlined some issues with Steiny DAW's properly managing multiple cores. The problem was somewhat masked with four cores but seemed to be highlighted with the introduction of Dual - Quads. The problem was most noticable when latencies dipped at and below 64 samples. For some reason the single Quads outperformed the Dual Quads - Steiny later came out and admitted that there were issues with the way their managed multiple cores.

http://www.nuendo.com/phpbb2/viewtop...317&highlight=

So many of the major DAW's have come out stating that they are multi-core ready but this technology is all so new I am wondering if the issues are only Steinbergs. When you couple the 'newness' of the technology with the fact that the two majors (Intel and AMD) have different CPU architectures I wonder if it is possible to make a blanket statement that your DAW (any DAW) is multi-core ready.

From a programming standpoint, is it a fairly simple task to make a DAW like Reaper multi-core ready?

Can DAW companies truthfully make blanket statements like Multi Core ready ?

Are there different considerations in programming for managing multi cores with AMD VS Intel chips?

Is there any forseeable issues in moving from 8 cores to lets say 16 cores ?

Thanks.

I can't speak too much for other DAWs since I'm not completely sure about how they do things internally, but I can tell you what I've seen.

REAPER is very good at utilizing multiple cores, especially when not doing live monitoring. The reason for this is that when possible, it will render each track slightly ahead of time, load balancing across CPUs.

Running item rendering, resampling, mixing, and FX ahead of time on multiple CPUs at the same time has some good advantages, in that as long as they stay ahead, the audio thread never really has to wait on it.

The downside is since the rendering happens ahead, real time user FX parameter changes can be delayed (by anywhere from 50-200ms) which can bother some people. Also UAD plug-ins for example don't like the out of order element of it, they expect all of their plug-ins to be called sequentially.

I'm going to go out on a limb here and say that from what I've seen, at least some other hosts tend to use a different model, that involves having to synchronize each CPU for every audio block.

In general fully utilizing multiple CPUs in a low latency fashion is a very difficult problem. We're planning on doing everything possible to improve it and support the top end hardware. We got one of the dual quads a few months ago for testing, and were pleased to see everything work quite well

-Justin

[True North]

Have you seen any performance issues with Reaper on your Dual-Quad VS a single Quad.

IOW - does a Dual Quad still have performance advantages over a single Quad while using Reaper at lower latencies - i.e. 128 samples and below

[Justin Frankel]

Originally Posted by True North

Have you seen any performance issues with Reaper on your Dual-Quad VS a single Quad.

IOW - does a Dual Quad still have performance advantages over a single Quad while using Reaper at lower latencies - i.e. 128 samples and below

The dual quad results in a nearly twice the available horsepower for FX

As far as lower latencies go, 128-256 samples have no problem using most of the 8 cores.. however using 512 sample blocks is definitely more stable, though this may be more of a function of the audio interface..

[True North]

Originally Posted by Justin Frankel

The dual quad results in a nearly twice the available horsepower for FX

How about I/O's use efficiencies ?

Originally Posted by Justin Frankel

As far as lower latencies go, 128-256 samples have no problem using most of the 8 cores.. however using 512 sample blocks is definitely more stable, though this may be more of a function of the audio interface..

From what you are saying, as far as plugin's are concerned, a dual quad is almost twice as capable as a single quad. To the lay person that would seem to make sense. So in other words and hypothetically speaking, if you maxed out your single quad system on 100 Rea-verb plugins - a dual quad system might max at something like 180 Rea-Verb plugins - Correct ?

What happens to these efficiencies when the latencies fall below 128 samples ?

Thanks

[Justin Frankel]

Originally Posted by True North

How about I/O's use efficiencies ?



From what you are saying, as far as plugin's are concerned, a dual quad is almost twice as capable as a single quad. To the lay person that would seem to make sense. So in other words and hypothetically speaking, if you maxed out your single quad system on 100 Rea-verb plugins - a dual quad system might max at something like 180 Rea-Verb plugins - Correct ?

What happens to these efficiencies when the latencies fall below 128 samples ?

Thanks

When I first got this 8 core machine, I did some tests comparing it to my previous dual core athlon64 at a similar clock speed.

I did most of the tests at 512 sample block size at 48khz.

I loaded tracks each with a mono WAV file, and a bunch of REAPER's built in FX (compressor, gate, FFT EQ, Convolution Reverb with a long sample, etc).

The dual core box could run around 13 of these. The 8 core box could run 50.


At lower blocksizes you can't quite push it as hard--as you start needing one of the processors to spend more time servicing the audio hardware.. But the overall performance is still quite pleasing

-Justin

[Ian Mac]

I am hugely impressed with reapers ability to utilize multiple cores, and the ability to manage this feature.

I just realized on my dual opteron ( 4 cores ) I can run more than 4 times as many realtime plugins than in Vegas.

Cpu load evenly distributed

That is significant ! 4 times more power for “free”

This is despite Vegas claim for better multi cpu support in v7 (only for video maybe)

I’m still only a follower of reaper, haven’t done a “real” project in it yet, but this discovery is a compelling reason to do one soon.