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advice from an Apple kernel developer
Authored by: hayne on Dec 08, '04 01:57:38PM
I found the following discussion in the archives of the Darwin development email list:
http://lists.apple.com/archives/darwin-development/2002/Aug/msg00441.html
The writer is/was apparently one of Apple's kernel developers and so presumably knows what he/she is talking about.

Summary:
Increasing the value of maxvnodes will increase the number of files that get cached in RAM. This will make subsequent access to those files much faster.

But the downside is that more of your RAM will be used up for this disk caching and thus you will have less RAM available for normal application use. Therefore you should only consider increasing maxvnodes if you always have lots of "free memory" as shown in 'top' or "Activity Monitor", and if you hardly ever get pageouts (also shown in 'top' or "Activity Monitor").

The default value is a compromise that is expected to result in the best overall performance for people using OS X as a "desktop OS" - i.e. for running GUI applications, etc.
If you are running OS X primarily for use as a server, or if your usage differs significantly from the norm, you might find it useful to tune the maxvnodes number. But only if you have a lot more RAM than is needed for the apps you run!

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