From 3046e2f5b79a86044ac0a29c69610d6ac6a4b882 Mon Sep 17 00:00:00 2001 From: Eliezer Tamir Date: Sun, 25 Aug 2013 10:23:46 +0300 Subject: [PATCH] net: add cpu_relax to busy poll loop Add a cpu_relaxt to sk_busy_loop. Julie Cummings reported performance issues when hyperthreading is on. Arjan van de Ven observed that we should have a cpu_relax() in the busy poll loop. Reported-by: Julie Cummings Signed-off-by: Eliezer Tamir Signed-off-by: David S. Miller --- include/net/busy_poll.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index 8a358a2c97e6a..829627d7b8460 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -123,6 +123,7 @@ static inline bool sk_busy_loop(struct sock *sk, int nonblock) /* local bh are disabled so it is ok to use _BH */ NET_ADD_STATS_BH(sock_net(sk), LINUX_MIB_BUSYPOLLRXPACKETS, rc); + cpu_relax(); } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && !need_resched() && !busy_loop_timeout(end_time));