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Re: 2.6.10 TCP troubles -- suggested patch

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: Re: 2.6.10 TCP troubles -- suggested patch
From: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Date: Sat, 12 Feb 2005 23:03:18 +0300
Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>, shemminger@xxxxxxxx, hubert.tonneau@xxxxxxxxxxxxxx, romieu@xxxxxxxxxxxxx, niv@xxxxxxxxxx, rick.jones2@xxxxxx, netdev@xxxxxxxxxxx
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Hello!

> set it to?  I think correct value is TCP_SKB_CB(skb)->end_seq.

Yup. But it does not matter. When it is not advanced, it does not make
PSHs more rare.

Actually, that anti-MacOS never worked well. If segment with forced PSH
was not transmitted in time, even forced PSHs could be deleted.
Your patch with setting PSH right before (or in) tcp_transmit_skb() must
work. Unless these segments are not tso.


> > I.e. let's disable TSO in 2.6.9 and look.
> 
> I believe this experiment had been performed already.

I saw only tests with TSO. And 2.6.9 showed exactly the same weird
behaviour. Only 2.6.9 did not slow start and we had only a few of 200msec
gaps.

Alexey


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