Logic Pro : does it use all cores and MT ?

[carambo]

Hello, I've read son many opposite opinions on this subject on different forum that I'm getting lost ! Does anyone know precisely if Logic would use any of 8 cores on a MP, or is it limited to 4 ? And does it use MT or not, since I read that on MacOSXForum : "However, Logic mainly depends on the floating point unit (FPU) inside the CPU and there is only one inside the CPU Core. Therefore HyperThreading means no gain for an application which is heavily bound to the FPU, because there is nothing to share. That is not a bug or a software limitation." ?
Thanks

 

[gigapower]

It can use mutli-core. There is a fine art in balancing plug-ins over your cores when doing heavy audio sculpting.

 

[craigcomposer]

logic core use

I just spoke to a logic engineer on the phone yesterday from apple. Logic can take advantage of all physical cores.

This is how it works:
Lets say you have an 8 core computer, the first eight tracks you load will use up one core each. When you load another 8 tracks each core then has 2 being processed on it. This is done so that tracks are processed simultaneously to alleviate any sort of processor latency.

The guy said that updates to utilize hyper threading could be coming soon but would not indicate when that might be.

 

[Ravich]

But logic DOES support hyperthreading, just not more than 8 cores.

So basically if you spend extra money on a Mac Pro with more than 4 cores, chances are it will perform worse in logic.

 

[carambo]

OK, thanks for your contribution and these important informations for those who are using Logic and plan to buy a MP. If I summarize :
- Logic does handle all cores available.
- But MT is available for quad core only (to achieve 8 through MT).
So I assume a good compromise would be the hexacore 3.33mhz, unless there is is an upgrade with Logic, but this is another story.

 

[gigapower]

Best rule of thumb, buy the biggest machine you can afford. You never know what will be coming next in terms of software.

 

[Ravich]

OK, thanks for your contribution and these important informations for those who are using Logic and plan to buy a MP. If I summarize :
- Logic does handle all cores available.

Logic handles up to 8 cores. Period. This can either mean 8 physical cores on an octad, 8 virtual cores on a quad, or even 8 virtual cores on an octad with 4 of the cores disabled.

- But MT is available for quad core only (to achieve 8 through MT).
So I assume a good compromise would be the hexacore 3.33mhz, unless there is is an upgrade with Logic, but this is another story.

While we dont know exactly how the hexacore will perform, we do know that if you have an 8 core mac pro and you disable 2 of the cores, it runs worse than if you disable 4 of the cores.

I would assume that Apple would want to release an update for Logic, given that now there is a hexacore mac pro, but you never know with Apple.

 

[Trailerman]

I'm in the same boat - also looking to upgrade for Logic use and trying to decide between 6 cores @ 3.33GHz or 12 cores @ 2.93 GHz.

I'm generally hearing that Logic can use as many physical cores as are present, but I'm still unlcear on whether 6 faster cores is going to yield better performance than 12 slightly slower ones. Personally (I currently use an 8 core MP) I tend to find that the overloads tend not to ocurr across all processors, but on one specific processor which might be handling a particularly onerous active task. That being the case, one wonders if 6 faster cores might be a better bet.

Then again, I'm currently running OS 10.5, so perhaps moving up to 10.6 at the same time as increasing the number of cores will offer better load balancing.

Any further input gratefully received.

Jules

 

[Ravich]

The people at the logic discussion forums say that according to logic benchmarks, the performance comparison between a 4 core (with HT) and an 8 core (no HT) at the SAME clock speed is 50 tracks and 57 tracks respectively.

So it's really not that big of a difference using physical cores vs virtual cores. Apple just needs to pony up with logic and get with the program.

 

[Trailerman]

FWIW I chatted with Apple last night, and was told categorically that Logic will use all cores of a 12 core machine. I verified that this had come from a pro-audio expert, and was told that it had.

They also said that Logic would deliver improved performance on a 12 core machine when compared to a 6 core machine. They gave no explanation for why that would be the case, but it stands to reason that if one were to run benchmarking tests with a whole bunch of identical tracks running identical plugins, then the current load balancing system of running one track on one core, and subsequent tracks on the next core ad infinitum would result in better benchmarks with more cores.

Whether this method of testing reflects a real world scenario is open to debate. I still think that most people who are maxing out their Mac Pros (myself included) will see overloads on one processor only, and that most other processors will see limited activity, but that's just my opinion. Ultimately I think you're right Ravich, that Apple need to sort out their processor affinity algorithms for Logic, so that it's able to balance loads in a more sophisticated manner than it does currently. If that were to happen then the 12 core would clearly be the best bet for CPU-heavy projects.

As things stand, which system will be best kind of depends on how you use Logic. I'm inclining towards the 12 core though.

Jules
http://www.trailermen.com

 

[Ravich]

FWIW I chatted with Apple last night, and was told categorically that Logic will use all cores of a 12 core machine. I verified that this had come from a pro-audio expert, and was told that it had.

You always have to be careful when you're talking with customer service reps about stuff that they have no reason to know anything about. They stand to gain nothing by asking their superiors for company flaws and then reporting them back to customers.

They also said that Logic would deliver improved performance on a 12 core machine when compared to a 6 core machine. They gave no explanation for why that would be the case, but it stands to reason that if one were to run benchmarking tests with a whole bunch of identical tracks running identical plugins, then the current load balancing system of running one track on one core, and subsequent tracks on the next core ad infinitum would result in better benchmarks with more cores.

Unless this discussion included information on clock speed, it is bull ****. We're not talking about plain old 6 vs 12. We're talking about 6 @ 3.33 vs 12 @ 2.66

Whether this method of testing reflects a real world scenario is open to debate. I still think that most people who are maxing out their Mac Pros (myself included) will see overloads on one processor only, and that most other processors will see limited activity, but that's just my opinion. Ultimately I think you're right Ravich, that Apple need to sort out their processor affinity algorithms for Logic, so that it's able to balance loads in a more sophisticated manner than it does currently. If that were to happen then the 12 core would clearly be the best bet for CPU-heavy projects.

As things stand, which system will be best kind of depends on how you use Logic. I'm inclining towards the 12 core though.

Jules
http://www.trailermen.com

I guess there's no point in supposing until people start receiving the Mac Pros and testing them out in logic. I'd just be extremely surprised if a hexacore functioned differently from an octad with 2 cores disabled.