From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750969Ab3L1FIP (ORCPT ); Sat, 28 Dec 2013 00:08:15 -0500 Received: from szxga01-in.huawei.com ([119.145.14.64]:64303 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750705Ab3L1FIN (ORCPT ); Sat, 28 Dec 2013 00:08:13 -0500 Message-ID: <52BE5CA0.40009@huawei.com> Date: Sat, 28 Dec 2013 13:07:44 +0800 From: Ding Tianhong User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Joe Perches , Eric Dumazet , Julia Lawall CC: "David S. Miller" , Netdev , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH net-next 19/20] net: plip: slight optimization of addr compare References: <52BD22ED.4030302@huawei.com> <1388159283.12212.80.camel@edumazet-glaptop2.roam.corp.google.com> <1388163982.30298.12.camel@joe-AO722> In-Reply-To: <1388163982.30298.12.camel@joe-AO722> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.72.199] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013/12/28 1:06, Joe Perches wrote: > On Fri, 2013-12-27 at 07:48 -0800, Eric Dumazet wrote: >> On Fri, 2013-12-27 at 14:49 +0800, Ding Tianhong wrote: >>> Use possibly more efficient ether_addr_equal >>> to instead of memcmp. > [] >>> diff --git a/drivers/net/plip/plip.c b/drivers/net/plip/plip.c > [] >>> @@ -549,7 +549,7 @@ static __be16 plip_type_trans(struct sk_buff *skb, struct net_device *dev) >>> >>> if(*eth->h_dest&1) >>> { >>> - if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0) >>> + if(ether_addr_equal(eth->h_dest, dev->broadcast)) >>> skb->pkt_type=PACKET_BROADCAST; >>> else >>> skb->pkt_type=PACKET_MULTICAST; >> >> What about : >> >> if (is_multicast_ether_addr(eth->h_dest)) { >> if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast)) >> skb->pkt_type = PACKET_BROADCAST; >> else >> skb->pkt_type = PACKET_MULTICAST; >> } > > That is better though I wonder how many systems are > still using laplink via parallel null-printer cables. > > No matter, better is better. > > The same optimization using ether_addr_equal_64bits > may be possible to do in other places given other > structs too. > > Perhaps it's a possible spatch/coccinelle conversion, > > I don't know spatch well enough to know if a > mechanism to check if structure members have other > fields that follow them in the structure or if the > structure member is an array of a minimum size. > > Maybe Julia does. (cc'd) > > As the below patch said, that a lot of ether_addr_equal could be instead of ether_addr_equal_64bits, and I need to review them and resend. Regards Ding >