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Re: TCP-Protection is really a pain...

To: Christian Schmid <webmaster@xxxxxxxxxxxxxx>
Subject: Re: TCP-Protection is really a pain...
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Thu, 3 Feb 2005 11:33:35 -0800
Cc: netdev@xxxxxxxxxxx
In-reply-to: <4201B4EA.2030101@xxxxxxxxxxxxxx>
Organization: Open Source Development Lab
References: <4201A382.1020208@xxxxxxxxxxxxxx> <20050202205437.571a702b@xxxxxxxxxxxxxxxxxxxxx> <4201B4EA.2030101@xxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Thu, 03 Feb 2005 06:21:46 +0100
Christian Schmid <webmaster@xxxxxxxxxxxxxx> wrote:

> Actually, thats my problem. Single streams are too slow! Before I had buffers 
> up to 500 KB. This was 
> very nice to CPU because I only needed to "push" more data once in 5 seconds. 
> I am doing this every 
> second now... *sigh* well maybe you might just want to add a /proc file in 
> order to configure this 
> behaviour.
> 
> btw: Another problem I am experiencing is that downloads suddenly break in 
> speed from 360 kb/sec to 
> 8-12 kb/sec. 5 seconds later they stall completely. But the interesting part 
> is, that the send-queue 
> is completely full (checked with a grep in netstat). This looks like as if 
> the receiver is just too 
> slow. But this is not the case. That makes it rather funny. The receiver is 
> waiting with an empty 
> pipe but linux doesn't send. What could this be?
>

Are you using a board that support TCP Segmentation Offload.  The problem may 
well be that
before we were not doing congestion control properly with TSO.  A pre-2.6.8 
host with TSO was violating
all sorts of RFC's and unfairly monopolizing bandwidth.

-- 
Stephen Hemminger       <shemminger@xxxxxxxx>

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