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

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Message-ID: <87lk487ol7.fsf@basil.nowhere.org>
Date:	24 Mar 2008 05:06:28 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Matti Aarnio <matti.aarnio@...iler.org>
Cc:	netdev@...r.kernel.org
Subject: Re: O(n^2) or worse ?   cat /proc/net/tcp

Matti Aarnio <matti.aarnio@...iler.org> writes:
> 
> I did observe odd slowness at first with  "lsof -p .."  program, 

You could oprofile it.

> then at
> "netstat -na".  Same slowdown happens with:  cat /proc/net/tcp
> (that 'cat' took 25 seconds...)

/proc/net/tcp should be only O(n^2) if the application does a lot of 
open()/seek()/read()/close() for very small chunks, but at least netstat
doesn't do that. Not sure about lsof though.

-Andi
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