lion -> mountain lion question

[grant howarth]

Hi all,
In anticipation for protools 11, i thought i would start trying to get my system updated from Lion 10.6.8 to Mountain Lion 10.8.3. I created the new install on a separate partition so i am able to switch back and forth between lion and mountain lion. Im running on a 12core mac pro. protools 10.3.2
The install of mountain lion was done by using carbon copy cloner to clone everything to the new partition and then i updated the OS on the new partition. So the protools installation is the same on both.

When i opened up some sessions that run fine in lion with a buffer setting at 64 samples i am getting errors right away when i try and play the session in mountain lion. Increasing the buffer setting to 128 fixes the problem but obviously i want to be able to continue to track confidently at 64samples.

After further testing if i leave it at 64 samples in mountain lion but i set the host processors to 18 instead of 22 (out of a total of 24) things seem to run properly. So my thinking in the past was leave one core for the OS and the rest for protools. Does it make sense that mountain lion needs more available processors to run properly? I notice that there are a lot more process running under mountain lion than lion. I have done the basic list of OS tweaks but i am wondering if there is something else i am missing of if anyone else has experience the same. Thanks greatly in advance for any help, - Grant Howarth.

[francois]

fresh install of both OS and PT is highly recommended on this one.

[grant howarth]

I did a fresh install of mountain lion and installed the latest version of protools. Same issue occurs. I guess mountain lion just needs more processors available and less used in protools.

[YYR123]

For what it's worth I have never left only 1 core for the OS

I have mine currently setup as 8 of 12 if I remember right @99%