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Re: _High_ CPU usage while routing (mostly) small UDP packets

To: Karsten Desler <kdesler@xxxxxxxxxx>
Subject: Re: _High_ CPU usage while routing (mostly) small UDP packets
From: Robert Olsson <Robert.Olsson@xxxxxxxxxxx>
Date: Tue, 7 Dec 2004 13:38:56 +0100
Cc: P@xxxxxxxxxxxxxx, "David S. Miller" <davem@xxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <20041207112139.GA3610@xxxxxxxxxx>
References: <20041206205305.GA11970@xxxxxxxxxx> <20041206134849.498bfc93.davem@xxxxxxxxxxxxx> <20041206224107.GA8529@xxxxxxxxxx> <41B58A58.8010007@xxxxxxxxxxxxxx> <20041207112139.GA3610@xxxxxxxxxx>
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Well my experience is that it very hard not to say almost impossible to 
extrapolate idle cpu into any network system capacity. I guess this is 
what you are trying to do? 

Rather load and overload the system with traffic having the characteristics
you expect as a bonus you will get some kind proof of robustness and 
responsiveness a max load. There are tools for this type of tests.

Pádraig! Very funny... I started hacking 2 hours ago on idea I 
had for long time, This to do a light version of skb recycling based
skb->users (the pktgen trick) with very minimal kernel change..

> Anyway attached is a small patch that I used to make the e1000
> "own" the packet buffers, and hence it does not alloc/free
> per packet at all. Now this has only been tested in one
> configuration where I was just sniffing the packets, so
> definitely YMMV.


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