docs: networking: timestamping: mention MSG_EOR flag

TCP got MSG_EOR support in linux-4.7.

This is a canonical way of making sure no coalescing
will be performed on the skb, even if it could not be
immediately sent.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231212110608.3673677-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/timestamping.rst b/Documentation/networking/timestamping.rst
index f17c01834a1230d31957112bb7f9c207e9178ecc..5e93cd71f99f1b17169b31f2ff93e8bd5220e5cd 100644 (file)
--- a/Documentation/networking/timestamping.rst
+++ b/Documentation/networking/timestamping.rst
@@ -357,7 +357,8 @@ enabling SOF_TIMESTAMPING_OPT_ID and comparing the byte offset at
 send time with the value returned for each timestamp. It can prevent
 the situation by always flushing the TCP stack in between requests,
 for instance by enabling TCP_NODELAY and disabling TCP_CORK and
-autocork.
+autocork. After linux-4.7, a better way to prevent coalescing is
+to use MSG_EOR flag at sendmsg() time.
 
 These precautions ensure that the timestamp is generated only when all
 bytes have passed a timestamp point, assuming that the network stack