[Spliff]

This tip was posted at MacOSXHints.com today.

Dramatically reduce the CPU usage of 'top'
_Fri, Feb 20 '04 at 10:09AM • from: axello

I always use the venerable top program in the Terminal to see which program is hogging the CPU. Unfortunately, most of the time it is top itself. Even on a fast 1 GHz dual-processor G4, top can take 20% of the CPU time. On FreeBSD, this is often less than 0.1%. I thought Apple would fix this in subsequent releases of Mac OS X, but I was wrong. It is probably something deeply rooted in the Darwin memory management core that prevents top from being fast, lean and mean.

I am mostly interested in CPU hogs, not in memory usage. Also I always sort on CPU usage, the default behaviour on other OSes. So I made a little shell script to make top use 5 to 10 times fewer CPU cycles. It basically removes all the memory checks from top, so you cannot use it to see how much memory a program occupies, or how much RAM you have left. Use the plain old top for that. This is what I use:

/usr/bin/top -ocpu -R -F -s 2 -n30

It sorts on CPU, it doesn't 'traverse the memory object map,' (a huge time saver), it doesn't calculate library statistics, it only redraws every other second and shows only the first 30 programs. You can put this line in a script called top in your ~/bin/ directory, or make it into an alias. Don't forget to rehash to make it work!

[robg adds: I created it as an alias (in tcsh) by adding

alias ttop 'top -ocpu -R -F -s 2 -n30'

(ttop can be whatever you like, of course) to my .tcshrc file, so I can run both versions easily. Even on my Dual G5, top is a CPU hog -- it takes about 10% - 15% of the CPU; using these command line switches, it's down around 1%.]

--Source: http://www.macosxhints.com/article.p...40213045335693

[[APi]TheMan]

Neat. Very nice. Very neat and nice. I normally top -u, yuck, it always did bug me how that took so much CPU time... I'll use it. Thanks for pointing out this gem, as I don't read macosxhints.com.

[Angus_D]

"top -ud" uses a lot less time here, too. And less typing.

[Link]

man top

Tons of useful info. My fav when I'm low on ram is top -o rprvt

[Don Pickett]

I use top -F -s 3, personally. I like to be able to see some memory usage stats, but I don't need an update every second.

[Vader’s Pinch of Death]

How much CPU does Activity viewer take?

[Don Pickett]

Originally posted by Vader’s Pinch of Death:
How much CPU does Activity viewer take?

Lots. It's a GUI over top with some additional stuff – it can track which processes are tied to which apps – but it's a process hog. I only use it when necessary.

[eevyl]

Originally posted by Vader’s Pinch of Death:
How much CPU does Activity viewer take?

In my current test bed (PowerMac G4 400mhz) with a alphabetically ordered list about 8%. If I set it to sort by CPU, so it is more dynamic, it can raise up to 10% often. This is with a 2 second poll time.