[ILUG] determining how much memory is shared between multiple
jm at jmason.org
Sun Oct 3 21:39:21 IST 2004
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Hi LUG --
I've run into a recurrent question, and hope there's an answer this time
Basically, I have a daemon process which forks N subprocesses, and I'm
trying to determine how much of the subprocesses' pages are being shared
with the parent, through copy-on-write.
top(1) seems to indicate that it can do that:
t: SHR -- Shared Mem size (kb)
The amount of shared memory used by a task. It simply reflects
memory that could be potentially shared with other processes.
but some investigation seems to indicate that on my 2.6.6 system, that
*only* applies to code pages loaded from shared libraries; pages allocated
on the heap are never listed in this field, even if they are unmodified
and therefore, presumably, shared.
(This may be a perl thing, though. the issue is SpamAssassin-related.)
If you take a look at
http://bugzilla.spamassassin.org/show_bug.cgi?id=3839 , you can see our
investigation so far, copies of /proc/*/maps, etc.
Anyone got any good tips for ways to figure this out?
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Comment: Exmh CVS
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