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USB connection raises preset CPU utilization by 5%

yek

Moderator
Moderator
I've been wondering why the CPU utilization of my presets differs from time to time.

I already discovered earlier that globally enabling/disabling Cabinet simulation has a LARGE impact.

And this morning I also found out connecting the Axe-Fx through USB impacts the CPU percentage.
There's about 5% difference with / without an USB connection.

Makes a lot of difference if a preset is already close to 90%. Things become sluggish or a CPU overload can occur.

May be useful to know this.
 
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jon

Fractal Fanatic
Yea, good info man, I'm just about ALWAYS maxing out my ultra, and doing things like deleting shunt blocks if I don't need them JUST to save that extra 1% cpu, and I suspect that I might get pretty close to max on the II as well when I get it, so thanks for this info.

I had some issues in the ultra where there was some little bleeps and bloops that came out when I crossed 95%, does that happen in the ii?
 

yek

Moderator
Moderator
Yeah, it's still possible to overload the device. Audio still works okay at about 96, 97% but the GUI is very slow at that point. And you wouldn't be able to use that preset when connecting over USB.

If you need extra CPU% and don't need the noise gate, switch that off (Ultra: Threshold 0, II: "Off"). Saves a couple of %.
 

jon

Fractal Fanatic
good advice, but I ALWAYS use a noise gate LOL even on clean patches. Matter of fact I was lobbying in the ultra wishlist for a global type noise gate or a global parameter to control the noise gate's threshold (inherent in each layout)

Any other good tips on saving CPU for the ii and/or the ultra? I'm all ears! :D
 

yek

Moderator
Moderator
I think you've covered it.
As you stated, deleting shunts also helps a little.

Also the type of effect maters. IIRC the Spring/Vintage reverb uses a lot more CPU cycles than the others on the Ultra (display shows incorrect %, it's actually higher ...).
 
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jon

Fractal Fanatic
How does the II read cpu? as an average of both the processors? or whichever is closest to being maxed etc? or do you get a display for them both?

Also, is the cab sim taken up by the processor that is modelling the amps?
 

yek

Moderator
Moderator
1 DSP is solely dedicated to Amp blocks.
All other effect blocks (incl. Cabs) use the other DSP.
Don't know how it operates.There's one CPU reading.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
The CPU reading is always the main DSP. The second DSP only handles amp modeling and cannot be overloaded. It is guaranteed to never be more than 80% or so.

USB does increase CPU utilization since it is a bit of a bus hog.
 

jon

Fractal Fanatic
awesome!!! :D

really puts things into perspective tho.....the g1 units use about 27-30% with just one amp, and about 48-50% with two amps (with no other blocks there), and the amp dsp will max the new units at 80% with only amp models....keep in mind that the G1 units would have had the cpu also handling other data at the same time....operating system, midi, display data, etc....really puts into perspective the detail in modeling that the G2 units go to! :eek:

well on paper anyways. when I get mine I'll be all to happy to test it out :D

for days and days on end.... :D
 

jon

Fractal Fanatic
do you mean when after using the axe via usb you disconnect the axe and the cpu goes up?
or when connected to the pc the cpu drops by 5%?
 

Enzo Sutera

Inspired
do you mean when after using the axe via usb you disconnect the axe and the cpu goes up?
or when connected to the pc the cpu drops by 5%?
It looks like a bug to me. If the axe is connected to the pc all is fine, if I disconnect the USB cable with the axe still powered on nothing changes. If I power off the axe and then on without an USB connection (for example at a gig) the CPU usage goes up by 5% and all becomes very slow.
 
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Alter Ego

Inspired
I haven't retested, but I think I've experienced this phenomena as well (where a patch that worked fine while connected via usb became problematic later when usb was not connected). Didn't realize at the time it was usb related, but that would make sense......
 

Alter Ego

Inspired
Just a followup to say this does appear to be an issue...yesterday I programmed a number of patches with axe-edit yesterday via Usb, they all worked fine...today had the Axe II out on a session and almost every patch displayed the 'cpu overload' message....
 
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