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 Post subject: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 1:04 pm 

Joined: Mon Aug 30, 2004 10:35 am
Posts: 348
Let me start by saying sorry - this kind of turned into a bit of a lengthy post... but I think it's an important issue.

Lately I've been frustrated by the state of multicore support in Live. Basically, depending on the specific content of a project, it's often the case that projects with a puny number of tracks can start to really produce major dropouts. I've got a 12-core Mac Pro. Power-wise this thing is a behemoth, but Live brings it to its knees well before it should do, on a consistent basis.

As an experiment, I set up a simple test project. U-he ACE is one of the most CPU-intensive synths around, especially when you start to stack voices, so I tried a simple test to gauge comparative CPU usage between Live and Reaper. In both cases I set it up like this:

- Audio interface buffer size = 512 samples
- Set up 1 VSTi track, playing a 1 bar monophonic MIDI sequence
- The VSTi used is u-he ACE on the default preset, but with
(a) "Stack" set to 8
(b) "Quality" set to "Accurate".
(c) No other plugins on the track - just the one instance of ACE.
- Duplicate that track until you start getting CPU dropouts during playback.

The results?

Live: 24 tracks is as far as I can go without issues. This makes sense since a 12-core machine with Hyperthreading = 24 virtual cores. Once I start playing a 25th track though, things grind to a RIDICULOUS halt - huge dropouts all over the place, the whole thing becomes unusable.

24 tracks is a very hard limit - it goes from sounding smooth to total stuttering garbage in the blink of an eye. This correlates to my anecdotal experience with other projects, where things all roll along very nicely to a point, when suddenly adding something innocuous (like an extra plugin here or a new track there) produces major dropouts all of a sudden.

Here is what OS X's CPU meter looks like:

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This is at 24 tracks - when things sound smooth

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This is at 25 tracks. Audio-wise there are massive dropouts, but notice 2 things. Firstly, CPU usage overall is still quite low. Secondly, it's actually lower than it was for 24 tracks. Why would that be the case? This is certainly weird.



Reaper: 64 tracks is where dropouts start to happen very occasionally, but it can go up to 70-ish tracks before it the dropouts really becomes problematic. By comparison, here's what OS X's CPU meter looks like when running with 64 tracks (when dropouts still aren't really happening majorly yet)

Image
That's more like it. Reaper is using more of the CPU's power overall.


This really paints the situation of Live's level of multicore support, and performance overall - it is far from ideal. In terms of CPU performance, once you start pushing beyond Live's apparent limit - which seems to be equal to (for a non-Hyperthreading CPU) or double (for a Hyperthreading CPU) the number of physical cores in your machine - things go downhill incredibly quickly.

The thing to note is that when Live starts to produce dropouts and crackles, it's Live that's starting to crumble, not the machine or the operating system. Live is the limiting factor here. We all have very capable multicore machines these days and Live isn't equipped to take full advantage of them right now. Our expensive machines aren't being used to anywhere near their full potential by Live at the moment.

Better/more modern multicore support is absolutely my #1 wish for the next version of Live. I really hope they dramatically improve the situation.


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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 1:35 pm 

Joined: Fri Oct 09, 2009 1:13 pm
Posts: 409
Location: Dallas, Tx
which is why im sitting on my "old" laptop until I hear about some dramatic advances in areas such as this.
The only program I run is Ableton...period. So unless that one program is going to truly utilize new tech...I'm not going to waste my money.


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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 4:15 pm 

Joined: Fri Jun 25, 2010 5:13 pm
Posts: 15
12 cores and dropouts? thats bad.. But so is the cruel world of supercomputing.

I lately switched on my old apple power pc with G3 acceleration card.. opened some old life and logic projects.. man.. that thing was flying... really strange how the little added functionality from the early 2000´s to now have slowed down the programs..

And the funny thing.. i had that experiance in the 90s allready when i timestreched an Emulator II sample with a mac plus..

the thing was flying.. and the stretch sounded ok..

I stick with my laptop since it falls to pieces, it actually allready started to do that.. and than go for well preserved a 1 year old second hand model.. anything else is a waste of money..
IMO


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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 4:44 pm 

Joined: Tue Feb 20, 2007 11:10 pm
Posts: 9998
70 instances of ace in 'accurate' mode playing in reaper ?!!!
8O 8O 8O

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 4:47 pm 

Joined: Tue Jun 15, 2010 10:46 am
Posts: 1541
Good information. Thx for sharing.

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 5:20 pm 

Joined: Tue Feb 20, 2007 11:10 pm
Posts: 9998
blö wrote:
12 cores and dropouts? thats bad.. But so is the cruel world of supercomputing.

I lately switched on my old apple power pc with G3 acceleration card.. opened some old life and logic projects.. man.. that thing was flying... really strange how the little added functionality from the early 2000´s to now have slowed down the programs..

And the funny thing.. i had that experiance in the 90s allready when i timestreched an Emulator II sample with a mac plus..

the thing was flying.. and the stretch sounded ok..

I stick with my laptop since it falls to pieces, it actually allready started to do that.. and than go for well preserved a 1 year old second hand model.. anything else is a waste of money..
IMO

hehe...
you are a wise one
1 step behind the pack..
took me a long time to realize that this is the way to go..
live one or two years in the past (technologically)..
let them youngsters spend their $$ on 'cutting edge' tech for me to buy a year later when something newer comes along..
8)

OP... your findings reminded me of this thread :
http://www.kvraudio.com/forum/viewtopic.php?t=333284

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 6:05 pm 

Joined: Tue Feb 20, 2007 11:10 pm
Posts: 9998
also relevant :
http://www.image-line.com/documents/new ... icore-cpus

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 8:12 pm 

Joined: Tue Sep 07, 2004 12:16 am
Posts: 15721
Location: New Orleans
^ I'm really looking forward to getting back to my FL Studio license once they release FL for Mac.

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 8:28 pm 

Joined: Tue Feb 20, 2007 11:10 pm
Posts: 9998
after trying the latest demo a bit.. and was left generally impressed..
if I had the extra $ .. I would probly buy it..
tons of fun.. and very powerful..reasonable price
performance was very smooth as well..no hiccups whatsoever !
(which is saying much..seems I'm somehow "used to" gui freezes for any simple action :wink: )

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 9:42 pm 

Joined: Mon Aug 30, 2004 10:35 am
Posts: 348
A couple points:

- Yep, 70 instances of ACE in Reaper... if only Live had that level of multicore support!!

- The Ableton CPU meter is incredibly erratic even when those 24 tracks are playing back smoothly in my test... it's even more erratic when the 25th track plays and the output becomes horribly dropout-ridden...

- That video about FL Studio is interesting... I totally understand that processor scheduling itself is handled by the operating system in ways that don't necessarily scale the same way as the CPU meter within Live (or any DAW), but that's largely not the issue here. The fact remains that :
(a) Reaper can deal with a lot more tracks than Live before you get dropouts, and
(b) Ableton has a hard limit when suddenly everything becomes unusable when adding just one more track, whereas Reaper just gradually gets more & more dropouts...

- In fact, that video shows that FL Studio works a lot more like Reaper than Live in its multicore implementation - as they add synths, the Windows CPU meters start to climb all the way up to max, just like Reaper does with the OS X CPU meter. By comparison, look the CPU meter readout for Live in my original post - not much going on at all, but that 25th track totally annihilates sound output with dropouts whilst the CPU usage apparently drops according to OS X. Something within Ableton isn't coping very well.

- Moreover, you can even totally ignore the CPU meter graphs. My argument here is not "OMG Live's CPU meter is lying to us because the OS X CPU meter says something different". Getting parity between Live and OS X's CPU meters isn't anything I'm concerned with. My whole concern is how far you can push Live, in terms of number of tracks/plugins, before you start getting ridiculous dropouts. Live isn't even using anywhere near the full amount CPU power available before catastrophic dropouts occur, whereas Reaper can be pushed a lot further, and by the looks of it, so can FL Studio.

- If Reaper can do it, it can be done. It's a matter of implementation. It seems there's something about Ableton's implementation that just really isn't good with fully utilising multicore systems.


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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 10:01 pm 

Joined: Fri Nov 19, 2004 6:48 pm
Posts: 1068
Location: Vienna
....i think something else i the reason for the peaks and dropouts! Have you set up the MacPro for audio? Turning off "Spotlight" for instance? I got the 8 Core MacPro and have newer been happier and I dont have any dropout even when using alot of synths and plugins.... :D

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Tue Nov 15, 2011 10:27 pm 

Joined: Mon Aug 30, 2004 10:35 am
Posts: 348
xzusa8ky - do you have u-he ACE? If not, grab the demo and try my test... it should start giving you problems on the 17th track by my estimation.


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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Wed Nov 16, 2011 3:48 am 

Joined: Sun Oct 21, 2007 10:59 pm
Posts: 1756
Location: 650 area
agree on having better implementation of the multicores.. I have the dual quad and i do at times get crackles/dropouts even though my native cpu meters tell otherwise.. but more of an issue is the RAM limitation.. hopefully Live 64 bit will not only address the memory issue, but also take better use of the cpu's..

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Wed Nov 16, 2011 5:13 am 

Joined: Tue Jun 15, 2010 10:46 am
Posts: 1541
I heard somewhere that the feature offering No audio dropout is related with the proccessing. It is when changing routing, insert effect/instrument and etc. To achieve this feature Live is probably handling audio signal odd way comparing to other daw. This may be the obstacle to obtain better multicore support, and cause less efficient multicore processing than that of the others.

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 Post subject: Re: Multicore support needs a big overhaul
PostPosted: Wed Nov 16, 2011 5:34 am 

Joined: Mon Sep 07, 2009 10:26 pm
Posts: 507
Having more than 4 cores is useless for everything except 3D renders and complex encoding. The time to send the information to each 12 cores between the ram, HD and cpus will nil any of the 12 cores advantages. Even Adobe admit that 4 cores is the sweet spot for top speed.

As for me, since I switched from reason to Live in 2009 on my i7 860 3.6ghz, I never had a single drop out using Asio4All. You sure it's not your comp/sound card/latency configuration?


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