On Mon, 13 Apr 2009, Stephen Hemminger wrote:
This is an alternative version of ip/ip6/arp tables locking using
per-cpu locks. This avoids the overhead of synchronize_net() during
update but still removes the expensive rwlock in earlier versions.
The idea for this came from an earlier version done by Eric Duzamet.
Locking is done per-cpu, the fast path locks on the current cpu
and updates counters. The slow case involves acquiring the locks on
all cpu's.
Doesn't spin_lock() result in a pipeline flush on x86?
iirc there was a benchmark in an RCU paper that tested using per cpu
spin_locks and the result was that it didn't scale well at all.
/Martin
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