Commit 8f7baad7 authored Sep 13, 2019 by Thomas Higdon Committed by David S. Miller Sep 16, 2019

tcp: Add snd_wnd to TCP_INFO



Neal Cardwell mentioned that snd_wnd would be useful for diagnosing TCP
performance problems --
> (1) Usually when we're diagnosing TCP performance problems, we do so
> from the sender, since the sender makes most of the
> performance-critical decisions (cwnd, pacing, TSO size, TSQ, etc).
> From the sender-side the thing that would be most useful is to see
> tp->snd_wnd, the receive window that the receiver has advertised to
> the sender.

This serves the purpose of adding an additional __u32 to avoid the
would-be hole caused by the addition of the tcpi_rcvi_ooopack field.

Signed-off-by: Thomas Higdon <tph@fb.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent f9af2dbb

include/uapi/linux/tcp.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -272,6 +272,10 @@ struct tcp_info {
		__u32 tcpi_reord_seen; /* reordering events seen */

		__u32 tcpi_rcv_ooopack; /* Out-of-order packets received */

		__u32 tcpi_snd_wnd; /* peer's advertised receive window after
		* scaling (bytes)
		*/
		};

		/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */

net/ipv4/tcp.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -3297,6 +3297,7 @@ void tcp_get_info(struct sock sk, struct tcp_info info)
		info->tcpi_dsack_dups = tp->dsack_dups;
		info->tcpi_reord_seen = tp->reord_seen;
		info->tcpi_rcv_ooopack = tp->rcv_ooopack;
		info->tcpi_snd_wnd = tp->snd_wnd;
		unlock_sock_fast(sk, slow);
		}
		EXPORT_SYMBOL_GPL(tcp_get_info);

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