From: Andrew Morton <akpm@linux-foundation.org>
To: netdev@vger.kernel.org
Cc: bugme-daemon@bugzilla.kernel.org, a@oo.ms
Subject: Re: [Bugme-new] [Bug 9031] New: TPC window is to cautious on send
Date: Sun, 16 Sep 2007 23:43:40 -0700 [thread overview]
Message-ID: <20070916234340.dfe2e94e.akpm@linux-foundation.org> (raw)
In-Reply-To: <bug-9031-10286@http.bugzilla.kernel.org/>
On Sun, 16 Sep 2007 17:02:46 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=9031
>
> Summary: TPC window is to cautious on send
> Product: Networking
> Version: 2.5
> KernelVersion: Any
> Platform: All
> OS/Version: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: IPV4
> AssignedTo: shemminger@osdl.org
> ReportedBy: a@oo.ms
>
>
> This has been a longstanding "bug" of sorts when talking to a system that has
> extremely small windows (under 1.5k).
>
> The only way to give the stack on the other side a nudge is to ACK twice.
>
> Here is a sample transcript, with a max window size of 1025 bytes.
>
> 18:25:43.968358 IP dr.ea.ms.http > 192.168.80.2.40246: . 37377:37633(256) ack
> 120 win 5840
> 18:25:43.992402 IP 192.168.80.2.40246 > dr.ea.ms.http: . ack 37121 win 769 <mss
> 256>
> 18:25:44.390305 IP 192.168.80.2.40246 > dr.ea.ms.http: . ack 37121 win 1025
> <mss 256>
> 18:25:44.823084 IP dr.ea.ms.http > 192.168.80.2.40246: . 37633:37889(256) ack
> 120 win 5840
>
> If I take the "nudge" code out of my IP stack, it sits for an aweful long time,
> waiting on the next packet, when there clearly is room for a few more.
>
> Should I:
> 1: Have my IP stack lie about the window till it is important?
> 2: Something else?
>
> I can't see any good reason for the large delay, since it is on a serial link,
> via SLIP.
>
> I can point you to source code that will allow you to verify the problem for
> yourself, if you would like.
>
next parent reply other threads:[~2007-09-17 6:44 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-9031-10286@http.bugzilla.kernel.org/>
2007-09-17 6:43 ` Andrew Morton [this message]
2007-09-17 17:03 ` [Bugme-new] [Bug 9031] New: TPC window is to cautious on send Stephen Hemminger
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