Messages in this thread | | | Date | Wed, 14 Feb 2007 01:01:26 +0300 (MSK) | From | malc <> | Subject | Re: CPU load |
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On Mon, 12 Feb 2007, Pavel Machek wrote:
> Hi! > >> The kernel looks at what is using cpu _only_ during the >> timer >> interrupt. Which means if your HZ is 1000 it looks at >> what is running >> at precisely the moment those 1000 timer ticks occur. It >> is >> theoretically possible using this measurement system to >> use >99% cpu >> and record 0 usage if you time your cpu usage properly. >> It gets even >> more inaccurate at lower HZ values for the same reason. > > I have (had?) code that 'exploits' this. I believe I could eat 90% of cpu > without being noticed.
Slightly changed version of hog(around 3 lines in total changed) does that easily on 2.6.18.3 on PPC.
http://www.boblycat.org/~malc/apc/load-hog-ppc.png
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