From patchwork Thu Aug 9 07:52:28 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Emelyanov X-Patchwork-Id: 176013 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 4B4162C00DA for ; Thu, 9 Aug 2012 17:52:44 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754371Ab2HIHwn (ORCPT ); Thu, 9 Aug 2012 03:52:43 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:1868 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755366Ab2HIHwk (ORCPT ); Thu, 9 Aug 2012 03:52:40 -0400 Received: from [10.30.16.117] ([10.30.16.117]) (authenticated bits=0) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id q797qTvf024557 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 9 Aug 2012 11:52:29 +0400 (MSK) Message-ID: <50236C3C.3040305@parallels.com> Date: Thu, 09 Aug 2012 11:52:28 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: David Miller , Eric Dumazet , "Eric W. Biederman" , Linux Netdev List , Ben Hutchings Subject: [PATCH 1/5] net: Dont use ifindices in hash fns References: <50236C20.4050108@parallels.com> In-Reply-To: <50236C20.4050108@parallels.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Eric noticed, that when there will be devices with equal indices, some hash functions that use them will become less effective as they could. Fix this in advance by mixing the net_device address into the hash value instead of the device index. This is true for arp and ndisc hash fns. The netlabel, can and llc ones are also ifindex-based, but that three are init_net-only, thus will not be affected. Many thanks to David and Eric for the hash32_ptr implementation! Signed-off-by: Pavel Emelyanov Signed-off-by: Eric Dumazet --- include/linux/hash.h | 10 ++++++++++ include/net/arp.h | 3 ++- include/net/ndisc.h | 3 ++- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/hash.h b/include/linux/hash.h index b80506b..24df9e7 100644 --- a/include/linux/hash.h +++ b/include/linux/hash.h @@ -67,4 +67,14 @@ static inline unsigned long hash_ptr(const void *ptr, unsigned int bits) { return hash_long((unsigned long)ptr, bits); } + +static inline u32 hash32_ptr(const void *ptr) +{ + unsigned long val = (unsigned long)ptr; + +#if BITS_PER_LONG == 64 + val ^= (val >> 32); +#endif + return (u32)val; +} #endif /* _LINUX_HASH_H */ diff --git a/include/net/arp.h b/include/net/arp.h index 7f7df93..b630dae 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -3,6 +3,7 @@ #define _ARP_H #include +#include #include @@ -10,7 +11,7 @@ extern struct neigh_table arp_tbl; static inline u32 arp_hashfn(u32 key, const struct net_device *dev, u32 hash_rnd) { - u32 val = key ^ dev->ifindex; + u32 val = key ^ hash32_ptr(dev); return val * hash_rnd; } diff --git a/include/net/ndisc.h b/include/net/ndisc.h index 96a3b5c..980d263 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -49,6 +49,7 @@ enum { #include #include #include +#include #include @@ -134,7 +135,7 @@ static inline u32 ndisc_hashfn(const void *pkey, const struct net_device *dev, _ { const u32 *p32 = pkey; - return (((p32[0] ^ dev->ifindex) * hash_rnd[0]) + + return (((p32[0] ^ hash32_ptr(dev)) * hash_rnd[0]) + (p32[1] * hash_rnd[1]) + (p32[2] * hash_rnd[2]) + (p32[3] * hash_rnd[3]));