netdev - Re: O(n^2) or worse ? cat /proc/net/tcp

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Message-ID: <20080324033329.GM3700@mea-ext.zmailer.org>
Date:	Mon, 24 Mar 2008 05:33:29 +0200
From:	Matti Aarnio <matti.aarnio@...iler.org>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: O(n^2) or worse ? cat /proc/net/tcp

On Sun, Mar 23, 2008 at 04:20:21PM -0700, David Miller wrote:
> From: Matti Aarnio <matti.aarnio@...iler.org>
> Date: Mon, 24 Mar 2008 00:43:07 +0200
> 
> > I have about 750 TCP socket on one multi-threaded server application, and 
> > about 250 on three single-threaded clients.
> > 
> > I did observe odd slowness at first with  "lsof -p .."  program, then at
> > "netstat -na".  Same slowdown happens with:  cat /proc/net/tcp
> > (that 'cat' took 25 seconds...)
> > 
> > Sure this is not earth shatterinly dangerous thing, rather a nuisance
> > when a monitoring application is not as fast as one would expect.
> 
> There have been some improvements in this area over the
> past few releases.
> 
> If you tell us what version you're running we can try to
> dig out the changes that matter.

Bleeding edgeish Fedora:

  2.6.25-0.90.rc3.git5.fc9 #1 SMP Tue Mar 4 20:19:33 EST 2008 x86_64 x86_64 x86_64 GNU/Linux

/Matti Aarnio
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