Slow write performance with Win 98 and Samba (fwd)
Christopher R. Hertel
crh at nts.umn.edu
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
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.
> I do this, to speed up Win->unix tcp/ip transfer.
> First, take a look at
> URL: http://www.dd.iij4u.or.jp/~okuyamak/Documents/tuning.english.html
> 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!
Christopher R. Hertel -)----- University of Minnesota
crh at nts.umn.edu Networking and Telecommunications Services
Ideals are like stars; you will not succeed in touching them
with your hands...you choose them as your guides, and following
them you will reach your destiny. --Carl Schultz
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