From 4b9d9be839fdb7dcd7ce7619a623fd9015a50cda Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 8 Jun 2011 13:35:34 +0000 Subject: inetpeer: remove unused list Andi Kleen and Tim Chen reported huge contention on inetpeer unused_peers.lock, on memcached workload on a 40 core machine, with disabled route cache. It appears we constantly flip peers refcnt between 0 and 1 values, and we must insert/remove peers from unused_peers.list, holding a contended spinlock. Remove this list completely and perform a garbage collection on-the-fly, at lookup time, using the expired nodes we met during the tree traversal. This removes a lot of code, makes locking more standard, and obsoletes two sysctls (inet_peer_gc_mintime and inet_peer_gc_maxtime). This also removes two pointers in inet_peer structure. There is still a false sharing effect because refcnt is in first cache line of object [were the links and keys used by lookups are located], we might move it at the end of inet_peer structure to let this first cache line mostly read by cpus. Signed-off-by: Eric Dumazet CC: Andi Kleen CC: Tim Chen Signed-off-by: David S. Miller --- include/net/inetpeer.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/inetpeer.h') diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h index 8a159cc3d68b..1f0966f91760 100644 --- a/include/net/inetpeer.h +++ b/include/net/inetpeer.h @@ -32,7 +32,6 @@ struct inet_peer { struct inet_peer __rcu *avl_left, *avl_right; struct inetpeer_addr daddr; __u32 avl_height; - struct list_head unused; __u32 dtime; /* the time of last use of not * referenced entries */ atomic_t refcnt; @@ -56,6 +55,7 @@ struct inet_peer { struct inetpeer_addr_base redirect_learned; }; struct rcu_head rcu; + struct inet_peer *gc_next; }; }; -- cgit