On Mon, 2013-03-25 at 12:59 -0400, David Miller wrote:

From: Eric Dumazet <redacted>
Date: Mon, 25 Mar 2013 09:54:32 -0700

quoted

On Mon, 2013-03-25 at 12:18 -0400, David Miller wrote:

quoted

This is effectively the default already, you don't need to change this
value explicitly.

->gso_max_size is set by default to 65536 and then TCP performs this
calculation:

                xmit_size_goal = ((sk->sk_gso_max_size - 1) -                          
                                  inet_csk(sk)->icsk_af_ops->net_header_len -          
                                  inet_csk(sk)->icsk_ext_hdr_len -                     
                                  tp->tcp_header_len);                                 

thereby making it adhere to your limits just fine.

For locally generated TCP traffic this is the case.

Right, and also any other piece of code that is not interpreting the
gso_max_size value the same way (as "(x - 1) - sizeof_headers") would
need to be fixed.

[...]

tcp_tso_should_defer() also ignores headers, though I don't think the
check is particularly critical in that case.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.