diff mbox

[v3,net-next,6/7] net: do not block BH while processing socket backlog

Message ID 1461964613-4872-7-git-send-email-edumazet@google.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet April 29, 2016, 9:16 p.m. UTC 
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 <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
---
 net/core/sock.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

Comments

Alexei Starovoitov April 29, 2016, 9:47 p.m. UTC | #1 
On 4/29/16 2:16 PM, Eric Dumazet wrote:
> 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<edumazet@google.com>
> Acked-by: Soheil Hassas Yeganeh<soheil@google.com>

Acked-by: Alexei Starovoitov <ast@kernel.org>
diff mbox

Patch

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