CPU usage clipping at 36% ????

laurence · Post by **laurence** » Sun Jul 25, 2010 4:57 am

Hey guys anyone else have this situation ? I have a Octo Core 2.8 Ghz Harpertown which seems to be clipping the CPU in the meter window and making clipping noises from the computer not being able to keep up but activity monitor says i'm only using 36% !!! !

I'm running at 64 samples on a PCIe 424 with a 2408 MkII ... Is this normal or is there something i'm missing... happens whether i'm in 10.5.8 or 10.6.4 the same.. using lots of plugins but doesnt seem to be the CPU's that are stressing ! ... love to know why, how what !!!
cheers

buzzsmith · Post by **buzzsmith** » Sun Jul 25, 2010 6:17 am

Does it do it if you raise the buffer to 256 or 512?

Buzzy

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David Polich · Post by **David Polich** » Sun Jul 25, 2010 9:39 am

A buffer setting of 64? Holy cow, that would explain it right there.

That buffer setting is just too low...I'd never run it at 64, even on
the most powerful Mac in existence.

YouTube · Post by **James Steele** » Sun Jul 25, 2010 1:45 pm

Yeah... 64 is really low. Cracks me up... But over in the Windows forum there's a thread where someone's complaining tat they are having problems running at 32!!!!

BTW, Laurence it still says you have a G5 in your sig. You may wish to update that.

Frodo · Post by **Frodo** » Sun Jul 25, 2010 5:08 pm

64 is pretty impressive, imho, with what was describe as "a lot of" plugins in use.

I say, if 64 is working fine to not worry about the CPU hit %. That's what the computer is for! If it's an 8-Core, then the machine is all the more up to the task.

I would only worry about the CPU hit when it goes over 70% at any point in the project. I say, let the computer work hard as it wants to, as long as it doesn't choke the project.

YouTube · Post by **James Steele** » Sun Jul 25, 2010 5:38 pm

Frodo wrote:I would only worry about the CPU hit when it goes over 70% at any point in the project. I say, let the computer work hard as it wants to, as long as it doesn't choke the project.

He's saying though that he's getting noises in his audio apparently. If that's the case bump it to 128. (This from a guy who always leaves his set to 1024!)

Shooshie · Post by **Shooshie** » Sun Jul 25, 2010 6:25 pm

A buffer of 64 was not practical in almost any way until the most recent machines. The next round or two of big breakthroughs in processing power may make latency a thing of the past, but for the time being ALL PC users are limited to the laws of physics as we know them. A buffer of 64 samples, with all those plugins, should be a marvel to contemplate that it works at all!

NEVERTHELESS… there may be things you can do to get that working. Closing other apps, killing processes that are checking the system periodically -- such as Spotlight -- may stop some of that clipping. If the level is staying at a usable figure, then suddenly jumping out of the park, leaving the clipping light on, then back to normal, it just may be a process you can kill and actually make 64 a usable option for you.

Shooshie

laurence · Post by **laurence** » Mon Jul 26, 2010 7:27 am

Thanks guys appreciate the reply ... Ok so get the picture that 64 is a bit hopeful but It seems quite useful to me as a reasonably large session runs well it's just that dp's CPU is going red and starting to clip when activity monitor says we're only using 36% of available power so I'm wondering why dp starts flaking out ages before the actual CPUs are being even 50% utilized ! I did another test in logic and it let's me load plenty more plugs etc at 32 and runs well .. I guess I'm just mythed as to why dp is telling me it's overloading CPU when I think it actually isn't overloaded !! Hmmm just curious as well as kinda interested to see if this is some setting I have wrong ! Anyone else care to dip their toes in the water ? Ps cheers Steve I thought I did but will do an update

YouTube · Post by **James Steele** » Mon Jul 26, 2010 9:56 am

laurence wrote:Thanks guys appreciate the reply ... Ok so get the picture that 64 is a bit hopeful but It seems quite useful to me as a reasonably large session runs well it's just that dp's CPU is going red and starting to clip...

So it's not running well then...

Whatever Logic is doing is interesting but probably won't help get DP working. What happens when you go to 128 buffer in DP? Have you tried that? I can't see switching from 64 to 128 making a huge difference in feel when playing VIs. Why do you need the buffer so low? Are you monitoring live inputs through plug ins?

You could keep trying to make it work on 64 as a matter of principle, or do this

and set it to 128 and be done with it. What is your work priority setting? You might experiment with that.

David Polich · Post by **David Polich** » Mon Jul 26, 2010 10:20 am

laurence wrote:Thanks guys appreciate the reply ... Ok so get the picture that 64 is a bit hopeful but It seems quite useful to me as a reasonably large session runs well it's just that dp's CPU is going red and starting to clip when activity monitor says we're only using 36% of available power so I'm wondering why dp starts flaking out ages before the actual CPUs are being even 50% utilized ! I did another test in logic and it let's me load plenty more plugs etc at 32 and runs well .. I guess I'm just mythed as to why dp is telling me it's overloading CPU when I think it actually isn't overloaded !! Hmmm just curious as well as kinda interested to see if this is some setting I have wrong ! Anyone else care to dip their toes in the water ? Ps cheers Steve I thought I did but will do an update

James pretty much answered your question. One more thing - you're saying the
CPU "clips", which I take it to mean you see it overloading in your activity
monitor, but you are NOT hearing audio clipping - correct?

I get CPU overload indicators (processor spikes) constantly but I just ignore them. Normally I run my buffer at 512 for tracking, 1024 for mixing. I'm on an old G5, and it is certainly nowhere near as powerful as your Mac...but what I'm saying is you can set DP's preferences so you don't get a notice when your CPU briefly overloads.

That said, I agree with James - don't expect DP to work like Logic, it doesn't. 128 is the minimum buffer size I'd use in DP.

YouTube · Post by **James Steele** » Mon Jul 26, 2010 10:28 am

Hey David, he did say "making clipping noises from the computer" in his original post I believe, so I'm assuming he is getting an audible glitch in DP.

David Polich · Post by **David Polich** » Mon Jul 26, 2010 11:53 am

James Steele wrote:Hey David, he did say "making clipping noises from the computer" in his original post I believe, so I'm assuming he is getting an audible glitch in DP.

Yes, you're right about that.

laurence · Post by **laurence** » Wed Jul 28, 2010 4:33 pm

Hey guys, thanks for all the thoughts ! It still really is a matter of why DP can't handle running at this setting when it is hardly using the CPU.. running on this setting means a lot of real time work can be done monitoring live and streaming between my HD rig VERY USEFUL !!! ... long complicated setup so wont bore you here but basically it myths me why my mac can run at 64 samples on the built in audio no problem with the same session ! yet as soon as i choose PCI 424 as the audio card it is bogged down with cpu load errors... all the while the cpu's in my mac are hardly even noticing a problem.. it seems this mac can run at 64 all day with loads more on it and reliably as long as i use the built in audio ... there's got to be a logical reason why a soon as i use motu interfaces i can't reliably use a buffer of 64... i understand saying just move to 128 etc.. but even at 128 the computer CPU's are underutilized before clipping happens as far as DP meter is concerned.. this spells to me that something is wrong with my setup or something... if anyone has a 8 core mac and wants to check out the situation i surely would be interested in seeing if they get the same results ??

YouTube · Post by **James Steele** » Wed Jul 28, 2010 6:38 pm

The only reason any of us "just say set it to 128" is we assumed you wanted to get your system working without having the problem. Does setting it to 128 eliminate it??

You can gladly pursue the whole theoretical world of "it should" this and "it should" that, but in the meantime you needed an answer yes?

Shooshie · Post by **Shooshie** » Wed Jul 28, 2010 8:05 pm

Macs run VERY fast at buffers of 128 or 256. I can actually perform music with a buffer of 1024, though it's hard to be accurate. But at 128 or 246 these MacPros really kick.

Shoosh

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