Commit 173b6d1c authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

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: default avatarEric Dumazet <edumazet@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231212110608.3673677-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 85c2674d

Documentation/networking/timestamping.rst

+2 −1
Original line number Diff line number Diff line
@@ -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