Thread (9 messages) 9 messages, 3 authors, 2009-09-01

Re: neighbour table RCU

From: Eric Dumazet <hidden>
Date: 2009-09-01 06:50:16

Stephen Hemminger a écrit :
Looking at the neighbour table, it should be possible to get
rid of the two reader/writer locks.  The hash table lock is pretty
amenable to RCU, but the dynamic resizing makes it non-trivial.
Thinking of using a combination of RCU and sequence counts so that the
reader would just rescan if resize was in progress.
I am not sure neigh_tbl_lock rwlock should be changed, I did not
see any contention on it.
The reader/writer lock on the neighbour entry is more of a problem.
Probably would be simpler/faster to change it into a spinlock and
be done with it.

The reader/writer lock is also used for the proxy list hash table,
but that can just be a simple spinlock.
This is probably is the only thing we want to do at this moment,
halving atomic ops on neigh_resolve_output()

But why neigh_resolve_output() was called so much in the bench
is the question...
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