netdev - Re: [PATCH net-next-2.6] filter: optimize sk_run

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Date:	Fri, 19 Nov 2010 18:16:24 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	hagen@...u.net, netdev@...r.kernel.org, xiaosuo@...il.com
Subject: Re: [PATCH net-next-2.6] filter: optimize sk_run_filter

Le vendredi 19 novembre 2010 à 09:05 -0800, David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Fri, 19 Nov 2010 17:55:59 +0100
> 
> > Unfortunatly on x86_32 it also chose that f_k was more valuable in a cpu
> > register and accumulator A lost its register to get a stack slot
> > instead.
> 
> Ok that tradeoff is terrible, but it depends upon knowledge we haven't
> given to the compiler (yet).
> 
> Let me think about this a bit...

By the way, I tried the 'register' keyword, and I knew it was a stupid
idea before even trying, since compiler ignored me : "What the hell do
you think you can tell me how to optimize this code ?"

(I am quite sure my laptop even smiled and sent to his neighbours a
broadcast saying "Hey buddies, this dumb guy tried the register C
keyword, isnt it funny ?")

Oh well...


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