netdev - Re: [PATCH net-next-2.6] net: harmonize the call to ptype_all and ptype

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Message-ID: <4D7542EF.5000201@gmail.com>
Date:	Mon, 07 Mar 2011 21:41:19 +0100
From:	Nicolas de Pesloüan 
	<nicolas.2p.debian@...il.com>
To:	Jiri Pirko <jpirko@...hat.com>
CC:	Nicolas de Pesloüan <nicolas.2p.debian@...e.fr>,
	netdev@...r.kernel.org, davem@...emloft.net, shemminger@...tta.com,
	eric.dumazet@...il.com, kaber@...sh.net, fubar@...ibm.com,
	andy@...yhouse.net
Subject: Re: [PATCH net-next-2.6] net: harmonize the call to ptype_all and
 ptype_base handlers.

Le 07/03/2011 11:03, Jiri Pirko a écrit :
> Sun, Mar 06, 2011 at 02:25:16PM CET, nicolas.2p.debian@...e.fr wrote:
>> Until now, ptype_all and ptype_base delivery in __netif_receive_skb() is
>> inconsistent.
>>
>> - For ptype_all, we deliver to every device crossed while walking the
>> rx_handler path (inside the another_round loop), and there is no way to stop
>> wildcard delivery (no exact match logic).
>> - For ptype_base, we deliver to the lowest device (orig_dev) and to the highest
>> (skb->dev) and we can ask for exact match delivery.
>>
>> This patch try and fix this, by:
>>
>> 1/ Doing exact match delivery for both ptype_all and ptype_base, while walking
>>    the rx_handler path.
>> 2/ Doing wildcard match delivery at the end of __netif_receive_skb(), if not
>>    asked to do exact match delivery only.
>>
>> Signed-off-by: Nicolas de Pesloüan<nicolas.2p.debian@...e.fr>
>> ---
>>
>> This apply on top of the last batch of patch from Jiri Pirko.
>> ---
>> net/core/dev.c |   32 ++++++++++++++++++++++++--------
>> 1 files changed, 24 insertions(+), 8 deletions(-)
>>
>
> I tend to like this patch. However I'm not sure if extra 2 loops don't
> introduce noticable overhead :/

I think ptype_all and ptype_base lists should only contain entries having ptype->dev == NULL.

The entries having ptype->dev != NULL should be on per net_device lists. The head of those lists 
could/should be in a ptype_all and a ptype_base property in net_device.

This would speed up the exact-match loops, because they would scan small (or empty) lists.

I need to double check the possible impact of this proposal.

	Nicolas.
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