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tcp: Add snd_wnd to TCP_INFO

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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>
This commit is contained in:
Thomas Higdon 2019-09-13 23:23:35 +00:00 committed by David S. Miller
parent f9af2dbbfe
commit 8f7baad7f0
2 changed files with 5 additions and 0 deletions
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4
include/uapi/linux/tcp.h
View File

@ -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 */

1
net/ipv4/tcp.c
View File

@ -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);