RE: [PATCH] tcp: disable tcp_autocorking for socket when TCP_NODELAY flag is set

[Salvatore Dipietro <dipiets@amazon.com>]

> It looks like the above disables autocorking even after the userspace
> sets TCP_CORK. Am I reading it correctly? Is that expected?

I have tested a new version of the patch which can target only TCP_NODELAY.
Results using previous benchmark are identical. I will submit it in a new 
patch version.

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -716,7 +716,8 @@

        tcp_mark_urg(tp, flags);

-       if (tcp_should_autocork(sk, skb, size_goal)) {
+       if (!(nonagle & TCP_NAGLE_OFF) &&
+           tcp_should_autocork(sk, skb, size_goal)) {

                /* avoid atomic op if TSQ_THROTTLED bit is already set */
                if (!test_bit(TSQ_THROTTLED, &sk->sk_tsq_flags)) {



> Also I wonder about these 40ms delays, TCP small queue handler should
> kick when the prior skb is TX completed.
>
> It seems the issue is on the driver side ?
>
> Salvatore, which driver are you using ?

I am using ENA driver.

Eric can you please clarify where do you think the problem is?