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Re: Current 2.6.x TSO state

To: Andi Kleen <ak@xxxxxxx>
Subject: Re: Current 2.6.x TSO state
From: John Heffner <jheffner@xxxxxxx>
Date: Fri, 1 Oct 2004 16:33:33 -0400 (EDT)
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>, <netdev@xxxxxxxxxxx>, <herbert@xxxxxxxxxxxxxxxxxxx>
In-reply-to: <20041001200102.GB23046@wotan.suse.de>
Sender: netdev-bounce@xxxxxxxxxxx
On Fri, 1 Oct 2004, Andi Kleen wrote:

> > As mentioned, the TCP receive buffer auto-tuning takes care
> > of all of this in 2.6.6 and later.  It's just 2.6.5 doesn't
> > have John Heffner's auto-tuning code which is why your test
> > case is so stuck in the mud.
> >
> > Also, the stretch ACK's are quite normal.  If the receiver can't
> > advertize a larger window, we won't spit out an ACK until
> > the ack timeout.
>
> Ok, but why is the TSO case still slower?

Because with TSO enabled, you get bigger back-to-back bursts during which
the receiving app can't run.

  -John


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