netdev - Re: [PATCH] net: filter: Convert the BPF VM to threaded code

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Message-ID: <4039f2893f574313ee14131c7f9961d3@localhost>
Date:	Tue, 09 Aug 2011 10:53:22 +0200
From:	Hagen Paul Pfeifer <hagen@...u.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, <rui314@...il.com>,
	<netdev@...r.kernel.org>
Subject: Re: [PATCH] net: filter: Convert the BPF VM to threaded code


On Tue, 09 Aug 2011 10:36:28 +0200, Eric Dumazet wrote:

 
> I am speaking of one single conditional branch, the one that is done for
> every BPF instruction done in a filter. It's never taken, so must be
> predicted by the cpu. A perf session could make sure it is  ;)

Ahh, ok - perf is your friend, I know Eric ;-)

>> > +		switch ((enum bpf_inst)fentry->code) {
>> 
>> That should not differ! Eric, sure that this do the trick?
> 
> It is the way to tell gcc to make its optimizations, if they exists on
> enum switch (), as David suggested.

Argl, I see sock_filter.code is declared as __u16 not enum.


Hagen
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