Message-ID: <422C66B8.2060605@rapidforum.com>
Date: Mon, 07 Mar 2005 15:35:36 +0100
From: Christian Schmid <webmaster@rapidforum.com>
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To: Ben Greear <greearb@candelatech.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: BUG: Slowdown on 3000 socket-machines tracked down
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Ben Greear wrote:
>> Its a full-duplex. Its a download-service with 3000 downloaders all 
>> over the world.
> 
> 
> So actually it's really mostly one-way traffic, ie in the download 
> direction.
> Anything significant at all going upstream, other than ACKs, etc?

Not much. See on the graph. The red is the downstream ;)

>> Yes. send-buffer to 64 kbytes and receive buffer to 16 kbytes.
> 
> 
> With regard to this note in the 'man 7 socket' man page:
> 
> NOTES
>        Linux assumes that half of the send/receive buffer is used for 
> internal kernel struc-
>        tures; thus the sysctls are twice what can be observed on the wire.
> 
> What value are you using for the sockopt call?

First I used 64 * 1024 but some months ago I checked with getsockopt and realized that it always 
gives twice of the value back. So I just have done 64 * 512 ;)

Chris
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