OT: Increasing Ethernet receive buffer size on a wintel laptop

I am sending as fast as I can over a 10 MbpS link data from
my (DPS) system to a wintel notebook. It will not go much
above 500 kbytes/sec., while when I receive things are OK.
The wintel system is giving me a low tcp window size, something
in the order of $4000 - and it does get full from time to time, which
is
the reason for the lower speed.
I managed to locate how to change the windows tcp window size, and
got it to $ffff. Well, it seems this was a "hard" ffff because the
handshake stopped - segments begun to get lost and the speed
degraded a lot (my retransmission is set pretty non-aggressively
so I can spot things like that when they occur).
The wintel network card "driver" can be set to have a receive
ethernet
buffer of up to 64k. Clearly it is too short - at the windows system
latencies it would be more than naive to expect tcp to process it
fast enough.
Is there a solution to that - I mean someone who has wrestled this
and would help? When it gets to windows I am just another TV-set user,
don't know much except what I have had to deal with.
The network adapter I can see is "Realtek RTL 8139 Family PCI
Fast Ethenrnet NIC", the CPU is a 1.4GHz Intel.

Thanks,

Didi

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On 2008-05-16 09:25:05 -0400, Didi <dp@tgi-sci.com> said:
[color=blue]
> The network adapter I can see is "Realtek RTL 8139 Family PCI
> Fast Ethenrnet NIC", the CPU is a 1.4GHz Intel.[/color]

I haven't had the world's greatest luck with Realtek NIC products, but
I'm not here to product bash - just my own experience. The driver
setting may not be what you're looking for, what you're probably
wanting to do here is to tweak the TCP settings in the Windows registry
to be more optimal for your connection type (LAN, DSL, T1, Other) to
the Internet.

A full discussion of all the parameters involved in this would be too
long, and frankly, not productive in the newsgroup. You have the right
idea, but the wrong set of settings you're trying to tweak.

Try this link below as a starting point:
[color=blue]
> [url]http://www.dslreports.com/drtcp[/url][/color]

While I'm not officially recommending this, you can probably find some
lively discussions on Windows TCP/IP tweaking in the forums accessible
there.

Tweaking Windows Registry settings is not light stuff - always take a
backup / perform a System Restore backup before changing things.
Windows doesn't like being changed - it just likes wasting CPU on silly
things. :P

/dmfh

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Digital Mercenary For Honor -2- wrote:[color=blue]
> ....
>
> Try this link below as a starting point:
>[color=green]
> > [url]http://www.dslreports.com/drtcp[/url][/color]
>[/color]

It did exactly what I had done before - set the tcp size to $ffff
(I put 65535 rather than 32768 in the box), modified the same
"registry entry" which I had formerly discovered and manually
created and deleted. Same effect of course - lost segments.
Windows TCP happily reports all the time a window size of
$ffff (I logged and checked that the first time, not now, but the
behaviour and everything else was 100% the same) and does
not manage to buffer all the incoming data.
I would have expected a 1.4 GHz intel processor to be able
to keep up with a saturated 10 MbpS channel, apparently not.
I have no problems doing that at a fraction of the horsepowers
I have on a 200 MHz PPC running DPS...
But I am not so keen on solving this, what matters to me is
that my part is OK, let MS worry about theirs, I can live
as things are. It would be nice if I could double the speed
towards that notebook but it is no life and death issue.

Thanks,

Didi

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Original message:[url]http://groups.google.com/group/comp.protocols.tcp-ip/[/url]
msg/4bfbe239013fd15f?dmode=source

On 2008-05-17 20:17:38 -0400, Didi <dp@tgi-sci.com> said:
[color=blue]
> But I am not so keen on solving this, what matters to me is
> that my part is OK, let MS worry about theirs, I can live
> as things are. It would be nice if I could double the speed
> towards that notebook but it is no life and death issue.[/color]


Indeed. This is personal bane of my I'd love to see you solve, since
only M$ products make it so difficult to change what are really basic
TCP/IP parameters (*growls with geek rage*). There is a "professional"
product called TweakMaster Pro that will allow you to get access to all
the parameters necessary to fine tune your Windows TCP/IP stack. It's a
number of parameters that need to be changed, not just one or two, and
unfortunately, M$ moves them around to different Registry entries from
time to time without documenting them.

Good luck to you.

/dmfh


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/ _` | ' \| _| ' \ 01100110 01101000
\__,_|_|_|_|_| |_||_| dmfh(-2)dmfh.cx