"faults" in Activity Monitor display

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Tim - 28 Nov 2004 18:03 GMT

Does anyone know exactly what the "faults" statistic is that you see
if you inspect a process in the OSX Activity Monitor? I assume this
is counting page faults? When I monitor my application under certain
conditions I see this incrementing at about 500 per second. I would
expect something like that would only happen when all real memory is
in use, and two applications are swapping in and out. Yet, I find I
have about 50 MB Free, and 64 MB Inactive. Does this make any sense?
Or, are these "faults" counting something else? Any suggestions where
I can learn more?

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Mike Hall - 29 Nov 2004 04:26 GMT

>Does anyone know exactly what the "faults" statistic is that you see
>if you inspect a process in the OSX Activity Monitor?

We could hope that the source is available at Apple's Darwin site...

> I assume this is counting page faults?

Hopefully they match some output from Apple's "vm_stat" command;
also see the 'vm_stat' man page.

Page faults happen for lots of reasons.

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Tony Walton - 30 Nov 2004 20:28 GMT

User-Agent: Unison/1.5.2

> Page faults happen for lots of reasons.

One of which, I believe, is reading files. Files are faulted in (on
Solaris, at least; I'm assuming the same applies to Darwin).

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Tony

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Mac Forum / Programming / Mac Programming / November 2004

"faults" in Activity Monitor display