CPU usage clipping at 36% ????

[laurence]

if i switch to the same test session to 128 playback works but is randomly clipping occasionally... this is showing 48% CPU utilisation on activity monitor... same thing switched to mac digital audio out from the mac pro sees same utilisation but it is just under clipping in DP and not making any clip noises... hmmmm so the audio driver software for the built in digital audio is more efficient than the PCIe card... and DP only allows me to use 48 % of the power i have.... perhaps it's not accessing all 8 cores ? maybe only using 4 and reporting incorrectly in activity monitor ?

The best result i can manage to get for it actually using my power from an 8 core machine is 56% using 256 samples buffer and multiplier of 3.... BTW: don't suppose either of you can explain the multiplier and what it actually does to enable better cpu handling ? does it affect latency ?

In every workstation i have owned before the 8 core i have found that when DP or other programs are reporting they are overloading that activity monitor shows cpu utilisation of something like 96% so i just don't understand why i can't get more out of it.... Does DP use all 8 cores or does it mainly use one or two ... do i have to turn on multiprocessor support somewhere or something ? i just dont get it...

thankyou so very much James and Shooshie for sticking with me and all my questions... i wish i could shout you a ice cold one or a warm brewed one to show my appreciation ! ..

Mat

[laurence]

just to add an interesting discovery.... if i pin DP with this session to just on the border of being overloaded (which with buffer of 256 etc is showing 48% usage in activity monitor) i can't get anything more out of DP but then i open imovie and encode a 10 minute DV footage clip and DP still works as it should with the occasional clip but imovie is using about 30% CPU because activity monitor now shows 75-80% utilisation.. so DP definitely ISN'T using my cpu's power properly in fact when DP says it is fully saturated it is only actually using half the power available to it regardless of the buffer setting...

Surely this is a problem in a setting on my part or DP is reserving itself for features / programming structures (MIDI, chunks etc) that i am not heavily using in this session ?

... .. anyway , i'll get over the topic after this final note we are after all supposed to be making music right * thanks again for chipping in !

cheers M