netdev - [PATCH net-next] tcp: autocork: take MSG

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Date:   Tue,  8 Mar 2022 21:47:06 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Martin KaFai Lau <kafai@...com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net-next] tcp: autocork: take MSG_EOR hint into consideration

From: Eric Dumazet <edumazet@...gle.com>

tcp_should_autocork() is evaluating if it makes senses
to not immediately send current skb, hoping that
user space will add more payload on it by the
time TCP stack reacts to upcoming TX completions.

If current skb got MSG_EOR mark, then we know
that no further data will be added, it is therefore
futile to wait.

SOF_TIMESTAMPING_TX_ACK will become a bit more accurate,
if prior packets are still in qdisc/device queues.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Martin KaFai Lau <kafai@...com>
Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
Cc: Willem de Bruijn <willemb@...gle.com>
---
 net/ipv4/tcp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 33f20134e3f19c1cd8a4046a2f88533693a9a912..b6a03a121e7694e3e8cc5b4f47b7954a341c966e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -688,7 +688,8 @@ static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
 	return skb->len < size_goal &&
 	       sock_net(sk)->ipv4.sysctl_tcp_autocorking &&
 	       !tcp_rtx_queue_empty(sk) &&
-	       refcount_read(&sk->sk_wmem_alloc) > skb->truesize;
+	       refcount_read(&sk->sk_wmem_alloc) > skb->truesize &&
+	       tcp_skb_can_collapse_to(skb);
 }
 
 void tcp_push(struct sock *sk, int flags, int mss_now,
-- 
2.35.1.616.g0bdcbb4464-goog