From 6b229cf77d683f634f0edd876c6d1015402303ad Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 8 Dec 2016 11:41:56 -0800 Subject: udp: add batching to udp_rmem_release() If udp_recvmsg() constantly releases sk_rmem_alloc for every read packet, it gives opportunity for producers to immediately grab spinlocks and desperatly try adding another packet, causing false sharing. We can add a simple heuristic to give the signal by batches of ~25 % of the queue capacity. This patch considerably increases performance under flood by about 50 %, since the thread draining the queue is no longer slowed by false sharing. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/udp.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/udp.h') diff --git a/include/linux/udp.h b/include/linux/udp.h index d1fd8cd39478..c0f530809d1f 100644 --- a/include/linux/udp.h +++ b/include/linux/udp.h @@ -79,6 +79,9 @@ struct udp_sock { int (*gro_complete)(struct sock *sk, struct sk_buff *skb, int nhoff); + + /* This field is dirtied by udp_recvmsg() */ + int forward_deficit; }; static inline struct udp_sock *udp_sk(const struct sock *sk) -- cgit