netdev - Re: [PATCH v5 1/2] tcp: Add TCP_INFO counter for packets received out-of-order

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Message-ID: <CADVnQynfwJ8HWstz-HAa7AMOGRhDC7nqKwMCKpe2Fvm7kUQgkA@mail.gmail.com>
Date:   Sat, 14 Sep 2019 11:43:25 -0400
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Thomas Higdon <tph@...com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Dave Jones <dsj@...com>, Eric Dumazet <edumazet@...gle.com>,
        Dave Taht <dave.taht@...il.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>
Subject: Re: [PATCH v5 1/2] tcp: Add TCP_INFO counter for packets received out-of-order

On Fri, Sep 13, 2019 at 7:23 PM Thomas Higdon <tph@...com> wrote:
>
> For receive-heavy cases on the server-side, we want to track the
> connection quality for individual client IPs. This counter, similar to
> the existing system-wide TCPOFOQueue counter in /proc/net/netstat,
> tracks out-of-order packet reception. By providing this counter in
> TCP_INFO, it will allow understanding to what degree receive-heavy
> sockets are experiencing out-of-order delivery and packet drops
> indicating congestion.
>
> Please note that this is similar to the counter in NetBSD TCP_INFO, and
> has the same name.
>
> Also note that we avoid increasing the size of the tcp_sock struct by
> taking advantage of a hole.
>
> Signed-off-by: Thomas Higdon <tph@...com>
> ---
> changes since v4:
>  - optimize placement of rcv_ooopack to avoid increasing tcp_sock struct
>    size


Acked-by: Neal Cardwell <ncardwell@...gle.com>

Thanks, Thomas, for adding this!

After this is merged, would you mind sending a patch to add support to
the "ss" command line tool to print these 2 new fields?

My favorite recent example of such a patch to ss is Eric's change:
  https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/commit/misc/ss.c?id=5eead6270a19f00464052d4084f32182cfe027ff

thanks,
neal