From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, nanditad@google.com,
ncardwell@google.com, maze@google.com, tore@fud.no,
therbert@google.com
Subject: Re: [PATCH net-next] tcp: dont drop MTU reduction indications
Date: Mon, 23 Jul 2012 00:59:03 -0700 (PDT) [thread overview]
Message-ID: <20120723.005903.2179205107462793469.davem@davemloft.net> (raw)
In-Reply-To: <1343029732.2626.10234.camel@edumazet-glaptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 23 Jul 2012 09:48:52 +0200
> From: Eric Dumazet <edumazet@google.com>
>
> ICMP messages generated in output path if frame length is bigger than
> mtu are actually lost because socket is owned by user (doing the xmit)
>
> One example is the ipgre_tunnel_xmit() calling
> icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
>
> We had a similar case fixed in commit a34a101e1e6 (ipv6: disable GSO on
> sockets hitting dst_allfrag).
>
> Problem of such fix is that it relied on retransmit timers, so short tcp
> sessions paid a too big latency increase price.
>
> This patch uses the tcp_release_cb() infrastructure so that MTU
> reduction messages (ICMP messages) are not lost, and no extra delay
> is added in TCP transmits.
>
> Reported-by: Maciej Żenczykowski <maze@google.com>
> Diagnosed-by: Neal Cardwell <ncardwell@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied, thanks Eric.
prev parent reply other threads:[~2012-07-23 7:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-23 7:48 [PATCH net-next] tcp: dont drop MTU reduction indications Eric Dumazet
2012-07-23 7:59 ` David Miller [this message]
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