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From: David Miller <davem@davemloft.net>
To: netdev@vger.kernel.org
Subject: [PATCH 0/3] ipv4 metrics super-sharing
Date: Fri, 28 Jan 2011 14:35:00 -0800 (PST)	[thread overview]
Message-ID: <20110128.143500.260088125.davem@davemloft.net> (raw)


As I mentioned a few days ago, we can "super-share" the metrics
in the most common case, which is that there are not explicit
metrics set for a route.

This makes the metrics all zero, which means we can just alias
the pointer to dst_default_metrics.

Most importantly, this means we avoid atomics on the fib_info ref
count at dst destroy time.

Depending upon the configuration, this can also save a non-trivial
amount of memory in the routing tables.  Honestly, I doubt that
sites entertaining routing tables with hundreds of thousands of
routes have any non-zero metrics specified. :-)

                 reply	other threads:[~2011-01-28 22:34 UTC|newest]

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