Activity Monitor

KKeys · Post by **KKeys** » Wed Mar 01, 2006 8:29 pm

First, I've been a lurker here for a while and I've really appreciated the info and tips from you guys. Some of them have saved me or gotten me out of a lot of grief.
I've been having troubles with cpu spikes that are similar, I'm guessing, to what some others have had. I've gone through the tip list and I've tried to optimize things as best as I could. The spikes still come every once in a while and I can't seem to predict how or when - not sure I'm going to fix that 100%. However, it seemed odd for me that the my cpu meter in DP would never climb above 50% for any length of time and normally sits at what looks like to be about 10-20%. I don't have a huge computer (see below) but even when I've piled on the tracks, 15-20, I still don't max out the cpu consistently (except for those unpredictable spikes). I recently opened my activity monitor when running DP and it showed that I normally had about 600-800 MB of system memory free. Also, it showed the cpu was maxing out even when DP's meter sat about 20%. I'm confused on the difference. Are these two meters monitoring something different? It would seem to me that they should align closely but these just don't on my system. Any guesses?

Kyle

DP, 4.61, PB 1.33, 1.25GB RAM, external 7200 lacie, m-audio 410, OS 10.4.5

giles117 · Post by **giles117** » Thu Mar 02, 2006 6:17 am

It Appears that DP hogs a certain percentage of the processor then uses that hogged percentage as it pleases. which in a basic laymen way descirbes the disparity between the activity monitor and DP performance monitor.

How it does it, I know not, but on my Dual I will watch DP eat up 90% of the Processor but only show 10% used during a typical tracking session. Perhaps it is a unix thing.....

Resonant Alien · Post by **Resonant Alien** » Thu Mar 02, 2006 7:33 am

I noticed the same thing about a year ago...had a few exchanges with MOTU Tech Support about it....they were blissfully unaware of this issue, and frankly didn't seem really concerned about investigating it, let alone fixing it, so I just dropped it after a while. I usually run with both DP's Performance Monitor and the Mac's Activity Monitor open unless I'm really chewing up CPU, then I close Activity Monitor to save a few cycles.

grimepoch · Post by **grimepoch** » Thu Mar 02, 2006 7:36 am

Questions:

Are you pulling from an external drive?
What Buffer size are you using?
What Work Priority?
How many Plugins? What kind?

Shooshie · Post by **Shooshie** » Thu Mar 02, 2006 9:03 am

giles117 wrote:It Appears that DP hogs a certain percentage of the processor then uses that hogged percentage as it pleases. which in a basic laymen way descirbes the disparity between the activity monitor and DP performance monitor.

How it does it, I know not, but on my Dual I will watch DP eat up 90% of the Processor but only show 10% used during a typical tracking session. Perhaps it is a unix thing.....

Well, I know nothing about how MOTU wrote their code for DP, especially how they handle CPU and RAM, but this pattern sounds very familiar: it's similar to how DP ran in the old days of the Classic MacOS. You had to balance your RAM very carefully in those days, allocating just enough for DP to run on, and then leaving the rest for it to use for audio recording. If you gave too much RAM to DP, you'd leave too little for the audio, and we all know what happened if you gave too LITTLE to DP. (crash)

So, if your description is indeed the way they wrote it, then it would make sense. The amount of the CPU reserved for DP would probably change if you set "work priority" for highest or lowest values. Maybe this was their way of getting around UNIX's capricious ways of reallocating CPU cycles at will--something that works great for networked processes, but lousy for real-time processing which cannot afford to miss a single digital sample.

From what I understand, and I think Magic Dave once verified this for me, setting the work priority too high has a similar effect as allocating too much RAM to DP in the old days in OS9; it leaves too little room for other processes which may also be essential to DP, such as plugins. Just guesses, but I think we can safely say that finding that sweet spot is the key to smooth operation. On CPU-challenged machines, you don't necessarily want to set the work priority to maximum.

Shooshie