From: "David S. Miller" <davem@davemloft.net>
To: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: netdev@oss.sgi.com
Subject: Re: way of figuring out total number of retransmitted packets on a TCP socket?
Date: Wed, 20 Oct 2004 15:53:52 -0700 [thread overview]
Message-ID: <20041020155352.1c9b70f6.davem@davemloft.net> (raw)
In-Reply-To: <20041020223547.GJ29583@xi.wantstofly.org>
On Thu, 21 Oct 2004 00:35:47 +0200
Lennert Buytenhek <buytenh@wantstofly.org> wrote:
> Some places in the TCP stack reset tp->retransmits to zero, or to
> one. Is it supposed to reflect the current number of retransmitted
> packets in the network?
Yes, timeout based retransmits in the network. It is reset typically
when the connection is healthy again and making forward progress on
the lost packets.
> > Retransmits which occur dynamically due to fast-retransmit
> > and other non-timeout based decisions are accounted for
> > in "tcpi_retrans", so that is probably the value you are
> > looking for.
>
> tcpi_retrans is taken from tp->retrans_out (looking at 2.6.8 here.)
> But that value gets set to zero in a lot of places in the networking
> as well, so it's probably not what I'm looking for either.
I agree. We could easily add the thing you are looking for. It's
just another statistic, zero'd at socket creation time and incremented
right under the line which reads:
/* Update global TCP statistics. */
TCP_INC_STATS(TCP_MIB_RETRANSSEGS);
in tcp_retransmit_skb().
I'll add this for you.
next prev parent reply other threads:[~2004-10-20 22:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-20 13:01 way of figuring out total number of retransmitted packets on a TCP socket? Lennert Buytenhek
2004-10-20 13:25 ` Baruch Even
2004-10-20 22:16 ` David S. Miller
2004-10-20 22:14 ` David S. Miller
2004-10-20 22:35 ` Lennert Buytenhek
2004-10-20 22:53 ` David S. Miller [this message]
2004-10-20 23:04 ` Andi Kleen
2004-10-20 23:07 ` David S. Miller
2004-10-20 23:27 ` Andi Kleen
2004-10-20 23:42 ` David S. Miller
2004-10-21 1:18 ` Arnaldo Carvalho de Melo
2004-10-20 23:44 ` Lennert Buytenhek
2004-10-20 23:44 ` David S. Miller
2004-10-21 9:01 ` Lennert Buytenhek
2004-10-21 4:37 ` David S. Miller
2004-10-26 13:47 ` Lennert Buytenhek
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