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Re: 2.6.10 TCP troubles -- suggested patch

To: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Subject: Re: 2.6.10 TCP troubles -- suggested patch
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Sat, 12 Feb 2005 11:41:32 -0800
Cc: shemminger@xxxxxxxx, hubert.tonneau@xxxxxxxxxxxxxx, romieu@xxxxxxxxxxxxx, kuznet@xxxxxxxxxxxxx, niv@xxxxxxxxxx, rick.jones2@xxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20050212141641.GA27456@yakov.inr.ac.ru>
References: <0525M9211@server5.heliogroup.fr> <20050211150420.74737b2e@dxpl.pdx.osdl.net> <20050211170740.2608419b.davem@davemloft.net> <20050212141641.GA27456@yakov.inr.ac.ru>
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On Sat, 12 Feb 2005 17:16:41 +0300
Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx> wrote:

> > This set of data frames you quoted are all full, and
> > are tightly interspaced.  It looks exactly like a TSO
> > frame, which we certainly set PSH on, but the TSO
> > engine is dropping it aparently.
 ...
> Or it was two one-segment frames.

Even ignoring my TSO changes, we should be seeing at a minimum
1/2 window PSH settings which we're not as far as I can tell.
(this is due to the forced_push() test in net/ipv4/tcp.c)

This also points out a bug in my TSO PSH patch, I should be
updating tp->pushed_seq shouldn't I?  Question is, what to
set it to?  I think correct value is TCP_SKB_CB(skb)->end_seq.

> I.e. let's disable TSO in 2.6.9 and look.

I believe this experiment had been performed already.  Stephen,
isn't that the case?

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