Live 4.01 & HT dis- or enabling..

[myztmuzic]

Hi, all!

Got a new prob when running Live 4.01 compared to Live 2.x-3.x:

After launching Live 4.01 as mainhost, i've discovered that the CPU-meter in Live 4.01 tip over around 70-90% and cause a lot af cracles. But NOT in the previous releases of Live.
The thing is, that my DAW is a steady, new fast & stable rig (my main pc's almost an "overkill"-machine, so no lack of anything..) - For the record, i work with computer-handling daytime (advanced, tho), so i know my DAW's not guilty of this - and the settings in my OS (XP-proSp1) has been optimized for audio, using all good & safe tricks in the book - and further tweaked by PowerStrip & other powertweaks/edits/adds - and those settings are NOT wrong - for sure!!

When i set the Affinity (in dev.man->processes) to ONE of the CPUs (nomatter which one - both CPU 0 & 1 "works", tho..The strange thing is that i never had to do this in ANY other versions of Live.. - Now, it's like new years eve when it comes to cracles/dropouts, running LESS tracks in Live 4.01 than the prevs. There, i can run a lot of tracks, infact up to 4 times more ( 24/48 ) than in Lives 4.01-release. - With NO cracles - and the "Affinity" can be left as is; HT-enabled, and all is smooth & sweet. So WHY does Live 4.01 demands the "Affinity" to be set to ONE of the CPUs?? - This is an upgrade, so it should cope with HT when a well respected brand like Ableton release a major upgrade in 2004 - i dare to say that the majority of computerbased DAW-runners, - well, i know thats sort of a bombastic statement, - but after my knowledge, the DAWs around the world are upgraded to HT-CPUs - Mostly!

I've tried loading almost (and ALL) of my audio-takes/clips into RAM-mode, to destress (!!) myIntelP43.2GhsPrescott with 2Gb of fast, twinned 400 RAM & UAD-1 DSP-card - so no stress caused by the effect. (ALL effects on UAD-1 now: masters/returns/tracks) - so my maincpu just handle the takes/samples/midi-automation and other minor midistuff.

Compared to Live 3.x, where i had to run all effects on the main CPU (before i got a UAD-1 card) - and it worked (and works) just fine. After setting the affinity to ONE of the CPUs in Live 4.01, the CPU-meter decrease, actually (more stable CPU-metering as well) - and that's pretty strange to me, since it doesn't in the prev. releases. There, i can simply ignore the whole HT-prob, cause there isn't any - like they cope with HT (and jezz, running a LOT more tracks as well..) - so WHY does this happen in the LATEST release?? - It doesn't make ANY sense at all..!

Any others seeing this prob..? I think this is very strange - since it's the latest release. Any that knows for sure that Live's HT-capable.??

regs,
jo

[Andreas Zapf]

Hi myztmuzic,

thank you for reporting. As you observed, Live's audio engine runs faster on a P4 when restricted to a single logical CPU, or with hyper-threading turned off in the BIOS.

I'll try to explain why: hyper-threading splits a single physical CPU into two logical CPUswhich share the same resources (like the first-level cache). Currently, Live's audio engine uses one logical CPU. The other CPU is idle, and Windows assigns it to Live's GUI (graphical user interface) when needed.

So both the GUI and the audio engine run simultaneously on the same physical CPU. Since the resources are shared between the two, some kind of competition results between GUI and audio engine. Thus, the GUI slows down the audio engine, when it is busy (try to minimize Live during playback - it should reduce audio drop-outs).


There are two ways to deal with this fact.

The best would be to let the audio engine use both logical CPUs (more technically: let the audio engine run multi-threaded) so the GUI wouldn't get CPU time while the audio engine is busy. This is on our improvement list, and it may be released in a future version, but it's a complex and time-consuming task, and we'll need to weigh it against other features.

The second way is to restrict Live to a single logical CPU as you reported. It has the same effect: the GUI gets no CPU time while the audio engine is busy, and audio performance increases.

We'll go the second way for now. With the next free update, Live will detect if hyper-threading is enabled and restrict itself to one logical CPU.

Keep in mind: this doesn't mean that Live will use just 50% of your processor's power. Instead, the audio engine will be faster because it can access all resources of the processor (unless you run another CPU consuming application at the same time).


Regards

[anti-banausic]

Andreas,
This is simply good news. Early on in beta testing, it was obvious that restricting hyper-threading machines to one CPU was advantageous in both reduction of crackling, and a slight decrease in the CPU load presented by LIVE.

So that is what I presently do, however, I do like the fact that programs such as SONAR are enabled to use hyper-threading (presumably how you just mentioned, one thread for GUI, the other strictly for audio), if this is done it would potentially make LIVE easier (if possible), better (if possible), and slightly more powerful for us P4 H/T guys.

Thanks for the heads up!

anti-banausic

[myztmuzic]

Thanx, Andreas!!

This will help a lot - nothing like good news as this

I'll stick to the second way, as i'm "used" to with Live 4.01 by now - it's a bit time-consuming, on stage, but the most important is that the dropouts gone!!
The HT-fix, as you mentioned, would be very-very-VERY welcome, if you guys at Ableton choose to take the job (..) and make Live 4 HT-capable! - It's a lot of HT-folks out there - like myself, that would be Very grateful if you folks choose to do this..!

I say this, cause like myself, a lot of Live-users runs other progs. in rewire-mode/other slave-mode(s) with Live as main-host - since it's a brilliant piece of "workstation", btw.. - like you say, a lot of other progs. run HT as a standard these days..

Well, thanx again - i'll try out the "minimize-when-playback-trick" asap!

Regs,
jo

[matheo]

Hi Andreas,

Is this Live 4-specific or is it also true for Live 3?

Thanks

[drez]

Woohoo! Thank you very much Ableton!

[myztmuzic]

Adnreas, can you tell when the next update will be released??

It's nice to know, due to the fact that live-performance have to be stable, so users like me, going live with Live, can be shure when we can be booked - cause i don't dare yet, since it doesn't sound well with some dropouts now&then - it will clear the hall..

Best,
jo

[nebulae]

Until the new release of Live that autodetects hyperthreading and assigns it's affinity to one processor, you can download a little utility called RunOnProcessorExplicitly 1.00. It's available at http://drn.digitalriver.com/category.ph ... sed%7CDESC

Basically, once installed, you create a shortcut to ROPE.exe, and then the PDF tells you what parameters to use. For me, it's the following:

"C:\Program Files\ROPE\ROPE.exe" -p 1 -n "C:\Program Files\Ableton\Live 4.0.1\Program\Live 4.0.1.exe"

In my example, -p determines the number of processors, and -n is the location of the application. You can even change the generic XP/2K icon by clicking on the Change Icon button and go to the Live exe to use the proper icon. Once you run it, it'll launch Live with the affinity set to CPU 1 only.

Let me know if this works for you. Good luck!

neb
[email protected][/url]

[myztmuzic]

Hi, nebulae!

Thanx for good advices! - In my case, i prefer to set the affinity myself, until the next upgrade's released (that should have been done already, by "the team"; they said it would be released within 14 days for 30 days ago..

So i'll be waiting until then to test the prog. you mention, if the upgrade doesn't help with the "affinity-problem".

Thanx again - it seem like a nice shot, anyway

Best,
jo

[Alex]

Hi myztmuzic,

indeed we wanted to release the bugfixe update earlier but it has been moved for several reasons. However it will be released this week.

regards,
Alex