Slow write performance with Win 98 and Samba (fwd)

Christopher R. Hertel crh at
Thu Jun 21 06:02:37 GMT 2001

Kenichi Okuyama wrote:
> Before I start connecting windows machine, I run
> # sysctl -w net.inet.tcp.delayed_ack=0
> and when finish, I do
> # sysctl -w net.inet.tcp.delayed_ack=1
> as root.

OpenBSD keeps statistics on delayed acks, but sysctl on that system does 
not understand this variable, so I can't test on any of the systems I 
have installed just now.

> BTW, I don't know about other *BSDs, whether they can handle this,
> or not. Also, I don't know if this is trully blocking the problem,
> or simply ( magically ) I havn't meet with the problem.

I do not know if it is the same problem or not.  I may be looking at two 
different problems.

The thing that confuses me is that, from the client perspective, 
security=user and security=server are supposed to look the same.  I need 
to look more closely at the differences in traces between the two.

> BTW-2:
> I do this, to speed up Win->unix tcp/ip transfer.
> First, take a look at
> URL:
> You read it? Ok.
> The story continues.
> When sending large data Win->unix directional, Windows will first
> send 2 packet, then wait for ack. Windows will not send third packet
> until ack arrives, or timeout occur.
> Unix side do not send ack immediately. This is called "delayed-ack".
> It waits for a while, looking for piggy-bag-able packet ( usually
> 10-100msec wait ).
> As result, Win->unix tcp/ip transfer can only send 2 packets per
> 10msec, if delayed-ack fully waited. Because this delay is usually
> controlled by jiffie, we usually have better chance, around 2
> packets per 5msec.
> By stopping "delayed-ack", you can have better performance.

Thanks for this information!

Chris -)-----

Christopher R. Hertel -)-----                   University of Minnesota
crh at              Networking and Telecommunications Services

    Ideals are like stars; you will not succeed in touching them
    with your choose them as your guides, and following
    them you will reach your destiny.  --Carl Schultz

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