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Re: bad TSO performance in 2.6.9-rc2-BK

To: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Subject: Re: bad TSO performance in 2.6.9-rc2-BK
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Thu, 30 Sep 2004 17:34:39 -0700
Cc: jheffner@xxxxxxx, ak@xxxxxxx, niv@xxxxxxxxxx, andy.grover@xxxxxxxxx, anton@xxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20040930001007.GB10496@gondor.apana.org.au>
References: <20040929162923.796d142e.davem@davemloft.net> <Pine.NEB.4.33.0409291945100.3434-100000@dexter.psc.edu> <20040929170310.46c58095.davem@davemloft.net> <20040930001007.GB10496@gondor.apana.org.au>
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So I was wondering what in 2.6.5 vs. current 2.6.x TCP could
be tripping up Andi's setup and I think I just found it.

If I disable /proc/sys/net/tcp_moderate_rcvbuf performance
goes down from ~634Mbit/sec to ~495Mbit/sec.

Andi, I know you said that with TSO disabled things go 
more smoothly.  But could you try upping the TCP socket
receive buffer sizes on the 2.6.5 box to see if that gives
you the performance back with TSO enabled?

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