Re: [PATCH net-next 1/3] tcp: do not try to defer skbs with eor mark (MSG_EOR)

[Neal Cardwell]

On Sun, Nov 11, 2018 at 9:41 AM Eric Dumazet  wrote:
>
> Applications using MSG_EOR are giving a strong hint to TCP stack :
>
> Subsequent sendmsg() can not append more bytes to skbs having
> the EOR mark.
>
> Do not try to TSO defer suchs skbs, there is really no hope.
>
> Signed-off-by: Eric Dumazet 
> Acked-by: Soheil Hassas Yeganeh 
> ---
>  net/ipv4/tcp_output.c | 4 
>  1 file changed, 4 insertions(+)

Thanks!

Acked-by: Neal Cardwell 

neal

[PATCH net-next 1/3] tcp: do not try to defer skbs with eor mark (MSG_EOR)

[Eric Dumazet]

Applications using MSG_EOR are giving a strong hint to TCP stack :

Subsequent sendmsg() can not append more bytes to skbs having
the EOR mark.

Do not try to TSO defer suchs skbs, there is really no hope.

Signed-off-by: Eric Dumazet 
Acked-by: Soheil Hassas Yeganeh 
---
 net/ipv4/tcp_output.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 
9c34b97d365d719ff76250bc9fe7fa20495a3ed2..35feadf480300cd061411d65257f06ee658daa3c
 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1944,6 +1944,10 @@ static bool tcp_tso_should_defer(struct sock *sk, struct 
sk_buff *skb,
if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
goto send_now;
 
+   /* If this packet won't get more data, do not wait. */
+   if (TCP_SKB_CB(skb)->eor)
+   goto send_now;
+
win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor);
if (win_divisor) {
u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
-- 
2.19.1.930.g4563a0d9d0-goog