Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753959Ab2KZD3X (ORCPT ); Sun, 25 Nov 2012 22:29:23 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:38745 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753816Ab2KZD3W (ORCPT ); Sun, 25 Nov 2012 22:29:22 -0500 From: ling.ma.program@gmail.com To: edumazet@google.com Cc: linux-kernel@vger.kernel.org, Ma Ling Subject: [PATCH RFC] [INET]: Get cirtical word in first 64bit of cache line Date: Mon, 26 Nov 2012 11:29:15 +0800 Message-Id: <1353900555-5966-1-git-send-email-ling.ma.program@gmail.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 68 From: Ma Ling In order to reduce memory latency when last level cache miss occurs, modern CPUs i.e. x86 and arm introduced Critical Word First(CWF) or Early Restart(ER) to get data ASAP. For CWF if critical word is first member in cache line, memory feed CPU with critical word, then fill others data in cache line one by one, otherwise after critical word it must cost more cycle to fill the remaining cache line. For Early First CPU will restart until critical word in cache line reaches. Hash value is critical word, so in this patch we place it as first member in cache line(sock address is cache-line aligned), and it is also good for Early Restart platform as well . Thanks Ling --- include/net/sock.h | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 4a45216..312cf31 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -128,10 +128,10 @@ struct net; /** * struct sock_common - minimal network layer representation of sockets - * @skc_daddr: Foreign IPv4 addr - * @skc_rcv_saddr: Bound local IPv4 addr * @skc_hash: hash value used with various protocol lookup tables * @skc_u16hashes: two u16 hash values used by UDP lookup tables + * @skc_daddr: Foreign IPv4 addr + * @skc_rcv_saddr: Bound local IPv4 addr * @skc_family: network address family * @skc_state: Connection state * @skc_reuse: %SO_REUSEADDR setting @@ -149,16 +149,16 @@ struct net; * for struct sock and struct inet_timewait_sock. */ struct sock_common { + /* skc_hash belongs to first member in sock with cache-line aligned*/ + union { + unsigned int skc_hash; + __u16 skc_u16hashes[2]; + }; /* skc_daddr and skc_rcv_saddr must be grouped : * cf INET_MATCH() and INET_TW_MATCH() */ __be32 skc_daddr; __be32 skc_rcv_saddr; - - union { - unsigned int skc_hash; - __u16 skc_u16hashes[2]; - }; unsigned short skc_family; volatile unsigned char skc_state; unsigned char skc_reuse; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/