From: Rick Jones <rick.jones2@hp.com>
To: Felix von Leitner <felix-linuxkernel@fefe.de>
Cc: Chuck Ebbert <cebbert@redhat.com>,
linux-kernel@vger.kernel.org, Netdev <netdev@vger.kernel.org>
Subject: Re: bizarre network timing problem
Date: Tue, 06 Nov 2007 13:12:13 -0800 [thread overview]
Message-ID: <4730D8AD.5060401@hp.com> (raw)
In-Reply-To: <20071102232332.GA5739@codeblau.de>
Felix von Leitner wrote:
> Thus spake Rick Jones (rick.jones2@hp.com):
>
>>Past performance is no guarantee of current correctness :) And over an
>>Ethernet, there will be a very different set of both timings and TCP
>>segment sizes compared to loopback.
>
>>My guess is that you will find setting the lo mtu to 1500 a very
>>interesting experiment.
>
> Setting the MTU on lo to 1500 eliminates the problem and gives me double
> digit MB/sec throughput.
I'm not in a position at the moment to test it as my IPoIB systems are offline,
and not sure you are either, but I will note that with IPoIB bits circa OFED1.2
the default MTU for IPoIB goes up to 65520 bytes. If indeed the problem you
were seeing was related to sub-mss sends and window probing and such, it might
appear on IPoIB in addition to loopback.
rick jones
prev parent reply other threads:[~2007-11-06 21:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-17 20:51 bizarre network timing problem Felix von Leitner
2007-10-17 21:17 ` Chuck Ebbert
2007-10-17 22:00 ` Felix von Leitner
2007-10-17 22:16 ` Rick Jones
2007-10-18 9:42 ` Felix von Leitner
2007-10-18 17:22 ` Rick Jones
2007-11-02 22:11 ` Felix von Leitner
2007-11-02 22:33 ` Rick Jones
2007-11-02 22:38 ` Felix von Leitner
2007-11-02 22:58 ` Rick Jones
2007-11-02 23:23 ` Felix von Leitner
2007-11-06 21:12 ` Rick Jones [this message]
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