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Re: Early SPECWeb99 results on 2.5.33 with TSO on e1000

To: Dave Hansen <haveblue@xxxxxxxxxx>
Subject: Re: Early SPECWeb99 results on 2.5.33 with TSO on e1000
From: "Martin J. Bligh" <Martin.Bligh@xxxxxxxxxx>
Date: Fri, 06 Sep 2002 09:29:50 -0700
Cc: "David S. Miller" <davem@xxxxxxxxxx>, hadi@xxxxxxxxxx, tcw@xxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx, Nivedita Singhvi <niv@xxxxxxxxxx>
In-reply-to: <3D78C9BD.5080905@xxxxxxxxxx>
References: <3D78C9BD.5080905@xxxxxxxxxx>
Reply-to: "Martin J. Bligh" <Martin.Bligh@xxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
> I thought that I already tried to explain this to you.  (although 
> it could have been on one of those too-much-coffee-days :)

You told me, but I'm far from convinced this is the problem. I think
it's more likely this is a side-effect of a server issue - something
like a lot of dropped packets and retransmits, though not necessarily
that.

> Something strange happens to the clients when NAPI is enabled on 
> the Specweb clients.  Somehow the start using a lot more CPU.  
> The increased idle time on the server is because the _clients_ are 
> CPU maxed.  I have some preliminary oprofile data for the clients, 
> but it appears that this is another case of Specweb code just 
> really sucking.

Hmmm ... if you change something on the server, and all the clients
go wild, I'm suspicious of whatever you did to the server. You need
to have a lot more data before leaping to the conclusion that it's
because the specweb client code is crap.

Troy - I think your UP clients weren't anywhere near maxed out on 
CPU power, right? Can you take a peek at the clients under NAPI load?

Dave - did you ever try running 4 specweb clients bound to each of
the 4 CPUs in an attempt to make the clients scale better? I'm 
suspicious that you're maxing out 4 4-way machines, and Troy's
16 UPs are cruising along just fine.

M.


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