netdev - [PATCH] NET : UDP can use sk

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Date:	Fri, 9 Feb 2007 18:44:16 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: [PATCH] NET : UDP can use sk_hash to speedup lookups

In a prior patch, I introduced a sk_hash field (__sk_common.skc_hash)  to let 
tcp lookups use one cache line per unmatched entry instead of two.

We can also use sk_hash to speedup UDP part as well. We store in sk_hash the 
hnum value, and use sk->sk_hash (same cache line than 'next' pointer), 
instead of inet->num (different cache line)

Note : We still have a false sharing problem for SMP machines, because 
sock_hold(sock) dirties the cache line containing the 'next' pointer. Not 
counting the udp_hash_lock rwlock. (did someone mentioned RCU ? :) )

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>

View attachment "udp_can_use_sk_hash.patch" of type "text/plain" (2587 bytes)