From 5413d1babe8f10de13d72496c12b862eef8ba613 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 29 Apr 2016 14:16:52 -0700 Subject: [PATCH] net: do not block BH while processing socket backlog Socket backlog processing is a major latency source. With current TCP socket sk_rcvbuf limits, I have sampled __release_sock() holding cpu for more than 5 ms, and packets being dropped by the NIC once ring buffer is filled. All users are now ready to be called from process context, we can unblock BH and let interrupts be serviced faster. cond_resched_softirq() could be removed, as it has no more user. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- net/core/sock.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/net/core/sock.c b/net/core/sock.c index e16a5db853c6..70744dbb6c3f 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2019,33 +2019,27 @@ static void __release_sock(struct sock *sk) __releases(&sk->sk_lock.slock) __acquires(&sk->sk_lock.slock) { - struct sk_buff *skb = sk->sk_backlog.head; + struct sk_buff *skb, *next; - do { + while ((skb = sk->sk_backlog.head) != NULL) { sk->sk_backlog.head = sk->sk_backlog.tail = NULL; - bh_unlock_sock(sk); - do { - struct sk_buff *next = skb->next; + spin_unlock_bh(&sk->sk_lock.slock); + do { + next = skb->next; prefetch(next); WARN_ON_ONCE(skb_dst_is_noref(skb)); skb->next = NULL; sk_backlog_rcv(sk, skb); - /* - * We are in process context here with softirqs - * disabled, use cond_resched_softirq() to preempt. - * This is safe to do because we've taken the backlog - * queue private: - */ - cond_resched_softirq(); + cond_resched(); skb = next; } while (skb != NULL); - bh_lock_sock(sk); - } while ((skb = sk->sk_backlog.head) != NULL); + spin_lock_bh(&sk->sk_lock.slock); + } /* * Doing the zeroing here guarantee we can not loop forever -- 2.20.1