Mac OS X CPU Usage: Puzzling

Posted by Pierre Igot in: Macintosh
March 1st, 2003 • 12:33 am

This afternoon, I was using my Power Mac G4 (MDD) for regular work, and couldn’t help but notice that some operations were a tad sluggish.

Because of my long experience with using Mac OS X on a significantly slower machine (a Power Mac G4/450), where every percentage of available CPU power would count, I usually have two CPU monitoring tools open at all times: Mac OS X’s own Process Viewer application (with a refresh rate of 10 seconds), and Alex Harper’s excellent Menu Meters application, which puts a variety of indicators in your menu bar — including, in my case, processor gauges for both of my G4’s two G4 processors.

As things were definitely on the sluggish side, I took a look at the Menu Meters indicators first. To my surprise, they were both at or close to 100% at all times, with most of the CPU power monopolized by system operations (and not user operations). Suspecting an error in Menu Meters, I looked at things in Process Viewer, and could not find any process beyond 10% of CPU usage, even after HAVING waited through several refresh cycles. A typical process listing would include the following, in decreasing order:

A picture named CPU-Usage.jpg

As you can see, there is a clear discrepancy between what Process Viewer tells me and what Menu Meters tells me above in the menu bar. (The blue percentages represent CPU power used by user processes. The red percentages represent CPU power used by system processes. Since my G4 has two 1.25 GHz G4 processors, I get two series of numbers in the menu bar.)

Even taking INTO account the possible lack of synchronization between the refresh rates of Menu Meters and the refresh rate of Process Viewer, the discrepancy does not make sense. How can I be using almost 100% of the available CPU power according to Menu Meters and only approximately 20% according to Process Viewer?

Interesting, this is still happening as we speak, as I am typing this particular blog entry. I have yet to log out or restart my machine in ORDER to eliminate the problem. It’s still there. I can still use my machine, since it’s quite powerful and is still usable even when CPU power is getting scarce. But it’s very strange.

Of course, since my computer is somewhat sluggish, I would tend to suspect that the more accurate reading is Menu Meters’. But that doesn’t tell me what might be eating up all these CPU cycles without showing up in Process Viewer! Let’s see what I have open here:

Default Folder
Acrobat Reader
Internet Explorer
Word X
Print Center
System Preferences
iView Media Pro
Password Retriever
Spell Catcher X
NetNewsWire Lite
Adobe Photoshop

That’s it. I suppose I’m going to have to try and quit each application one at a time and see what happens. I just quit Photoshop, which usually eats some percentage of CPU power even when it’s sitting idle doing nothing. No changes.

I suspect that things will stay way up until I log out or restart.

Very strange.

The only thing I can think of is that “LittleSnitch” application that I installed the other day, just to try it out. Earlier this morning, when I woke my machine from deep sleep (the machine is too noisy to leave it on during the night), I noticed that it was eating CPU cycles like crazy (more specifically the “LittleSnitchDaemon” background application). So I force-quit it through Process Viewer. And things seemed to go back to normal at the time. The LittleSnitchDaemon application is no longer visible in Process Viewer. Could it still be part of the problem?

I guess I’ll never know… But I’m uninstalling LittleSnitch, that’s for sure. Too bad, because it looked like a good little application.

7 Responses to “Mac OS X CPU Usage: Puzzling”

  1. Pierre Igot says:

    The “cute” progress bars do indeed take a lot of CPU power, in a rather wasteful fashion. But that was not the problem here. The problem here was a discrepancy between what the Process Viewer application reported and what the actual CPU usage was. Anyway, that was a long time ago. Can’t say I have been able to reproduce the problem since…

  2. Nicky McLean says:

    Humm, I have noticed that a surprising ampount of cpu activity is needed to animate the cute “progress bars” of the aqua interface. Like, 10%cpu I think, but I don’t have a mac to retest this. (It was the Franglais seti logging application for macs, and of course, I want as much seticrunching as possible, thus I kept the window minimised)

  3. Joe Wize says:

    Very interesting, I Have dual g4 1.25 Gig OSX 10.2. My machine for the last week has been running very sluggish. I also cheked the process viewer and to my surprise Finder was at 144% and hogging up all my CPU power. I don’t have anything animated on my desk top and according to Finder nothings running except Finder. I used the computer only for music production. Does anyone have any ideas? I’m at my wits end.

  4. Joe says:

    Well after doing reseacrh I’ve found the problem. It’s the preferences folder of finder meaning user:(yourname) I deleted the preferences from finder and it reset and now no problem. The only thing you have to reset some of your preferences. Hope it works..

  5. brian.dowtion says:

    I’ just have discovered the same thing about my finder — up to 90% cpu usage .just sitting there…

    Will have to hunt this down…

  6. brian.dowtion says:

    Thanks Joe..
    After a 2 hour hunt last night. I came across that answer.. it works! Its like I have a new machine.

    The thread on Apple->Support->Discussions
    Recommended moving username/Library/Preferences to like your desktop..
    I have been able to copy back my Mail ( with no Ill effect as of yet.
    I think I’ll leave the others alone.

    Thanks again!

  7. Ed says:

    FYI…. the discussion thread that Brian refers to is here:

    But that thread does not cover the discrepancy between Activity Monitor and Menu Meters. My activity monitor shows sane CPU usage while menu meters shows ~99%.


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