Definitive answer needed on Host Processors settings

[Skytouch]

Page 63 of the Pro Tools Reference Guide says:

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"From the Host Processors pop-up menu, select the number of available processors you want to allocate. The number of processors available varies depending on how many processors are available on your computer:

* Select 1 Processor to limit host processing for Pro Tools to one CPU in the system.

* Choose 2 Processors to enable load balancing across two available processors for Pro Tools host processing tasks.

* On systems running four or more processors, choose the number of processors for Pro Tools host processing tasks."

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In listing # processors, is Pro Tools counting cores or "virtual cores" in the options it displays in the Playback Engine / Host Processors dropdown?

In other words, with my 6-Core Mac, should I never select 7-12 in this dialog, or would the dialog offer up to 24 "cores" to someone running a 12-Core Mac? Does Pro Tools recognize what model is running and change this dropdown?

Thanks,
Sky

[lincol1]

Pro Tools sees available processor cores and refers to them as processors in the playback engine window. My dual processor, quad core shows up as four processors in PT. Everything I have read has suggested leaving at least one free for system related tasks. So I have mine set to three cores.

[Skytouch]

Thanks Lincoln, that is the information I was looking for.

Regards,
Sky

[thin ice]

I remember having issues with some virtual instruments until I left one processor for the system.

[Jeffrey Talbot]

Yeah... assigning ALL your processors to PT is not the way to go.

[KMcK]

Originally Posted by Jeffrey Talbot

Yeah... assigning ALL your processors to PT is not the way to go.

Works fine for me.

[Darney]

Originally Posted by Skytouch

Page 63 of the Pro Tools Reference Guide says:

-----
"From the Host Processors pop-up menu, select the number of available processors you want to allocate. The number of processors available varies depending on how many processors are available on your computer:

* Select 1 Processor to limit host processing for Pro Tools to one CPU in the system.

* Choose 2 Processors to enable load balancing across two available processors for Pro Tools host processing tasks.

* On systems running four or more processors, choose the number of processors for Pro Tools host processing tasks."

-----
In listing # processors, is Pro Tools counting cores or "virtual cores" in the options it displays in the Playback Engine / Host Processors dropdown?

In other words, with my 6-Core Mac, should I never select 7-12 in this dialog, or would the dialog offer up to 24 "cores" to someone running a 12-Core Mac? Does Pro Tools recognize what model is running and change this dropdown?

Thanks,
Sky

I've set up (in my quad core Xeon) 4 processors at 85%... so far no issues. But I'm going to try 3 at 100% just to see if there's a difference in performance.

[GordonFreeman]

I notice a very interesting thing with my quad mac pro (8 threads). For the sake of Native CPU floor measurements, I kept a template session with some instruments loaded, the buffer at 32 samples, and usage limit at 95% (to spike up the CPU bar and see small value differences better):

- Host Processors: 1
- CPU Native Perf: 46%
-- Host Processors: 2
-- CPU Native Perf: 32%
--- Host Processors: 3
--- CPU Native Perf: 27%
---- Host Processors: 4
---- CPU Native Perf: 24% <--- best performance at 4 Processors!
----- Host Processors: 5
----- CPU Native Perf: 32%
------ Host Processors: 6
------ CPU Native Perf: 33%
------- Host Processors: 7
------- CPU Native Perf: 34%
-------- Host Processors: 8
-------- CPU Native Perf: 29%

This is very interesting, because it seems to show that I'm getting WORSE CPU performance from the system when I select anything other than 4 cores. The curve doesn't improve in a linear way, as I expected.

I seem to remember that PT 10 came with a default value of 4 processors selected.
- Does this mean you should never give PT more than 4 processors to play with?
- Is a mathematical balance reached when the system and Pro Tools have exactly 50/50?
- Do people with 8 core Mac Pros (16 threads) get best performance at 4, 8 or 12 cores in playback setting?

I'd love to know more about the technical reasons for this.

[juhanni]

Originally Posted by GordonFreeman

I notice a very interesting thing with my quad mac pro (8 threads). For the sake of Native CPU floor measurements, I kept a template session with some instruments loaded, the buffer at 32 samples, and usage limit at 95% (to spike up the CPU bar and see small value differences better):

- Host Processors: 1
- CPU Native Perf: 46%
-- Host Processors: 2
-- CPU Native Perf: 32%
--- Host Processors: 3
--- CPU Native Perf: 27%
---- Host Processors: 4
---- CPU Native Perf: 24% <--- best performance at 4 Processors!
----- Host Processors: 5
----- CPU Native Perf: 32%
------ Host Processors: 6
------ CPU Native Perf: 33%
------- Host Processors: 7
------- CPU Native Perf: 34%
-------- Host Processors: 8
-------- CPU Native Perf: 29%

This is very interesting, because it seems to show that I'm getting WORSE CPU performance from the system when I select anything other than 4 cores. The curve doesn't improve in a linear way, as I expected.

I seem to remember that PT 10 came with a default value of 4 processors selected.
- Does this mean you should never give PT more than 4 processors to play with?
- Is a mathematical balance reached when the system and Pro Tools have exactly 50/50?
- Do people with 8 core Mac Pros (16 threads) get best performance at 4, 8 or 12 cores in playback setting?

I'd love to know more about the technical reasons for this.

I'm interested in this as well!

[BobbyDazzler]

Half the processors, minus 1, is my rule of thumb.