Performance issue?!

Marko Käning MK-MacPorts at
Wed Dec 22 15:52:23 PST 2010


I noticed a strange thing concerning the execution time of a simple filter program of mine which I ran on Mac OSX natively as well as in a Linux VM via Parallels on one and the same iMac.

Here are typical values I measured using time:

	MacOS X host system with MacPorts
	real		0m0.010s
	user	0m0.003s
	sys		0m0.003s

	OpenSUSE 11.2 VM on Parallels
	real		0m0.008s
	user	0m0.001s
	sys		0m0.007s

Firstly one sees that the "real"ly spent time is 20% shorter on the VIRTUAL Linux on my Parallels 5.0.

On the other hand I see that "user"+"sys" time is usually equal to "real" on Linux, whereas "user"+"sys"<"real" on Mac OS X itself, which makes me believe that "user"+"sys" is the more actual than "real". :-)
Assuming "user"+"sys" being the really consumed time by the system to run my little filter tool would proove then the Mac OS X host system to be slightly faster than the virtual Linux guest system, which I would have expected in the first place.
Nevertheless I am a little taken aback, confused, dazed due to these unexpected numbers here.

Any ideas as to what causes this?

Anyway, there is more to come… But I would like to hear your opinion on this topic first, before I dive into other results which are even more shocking. ;-)


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