From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Heinz <creatix@hipac.org>
Subject: Table duplication on smp machine
Date: Mon, 31 Mar 2003 12:52:06 +0200
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Hi

Netfilter maintains different tables for each cpu which is especially
interesting for smp ;-)

This is done - according to the docs - to avoid write locking.
Now, what would be write locked in case we had only one set of
rules:

a) counters
b) match/target write operations to their match/target data

a) is clear. b) not really: if a target/match needs to store
data it would do it the way the limit match does it which
requires an in-module lock mechanism and an ugly pointer in the
private data of the match/target.

Hm, remains a). There must be another reason. Otherwise a lot
of space is wasted just to keep separate per-cpu counter values.

Is there another reason?


Regards

Thomas