From patchwork Tue Sep 23 08:54:37 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 392277 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 E339C1400B2 for ; Tue, 23 Sep 2014 19:00:32 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754300AbaIWI77 (ORCPT ); Tue, 23 Sep 2014 04:59:59 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:22319 "EHLO mailhub1.si.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753337AbaIWI74 (ORCPT ); Tue, 23 Sep 2014 04:59:56 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id E3A171C8509; Tue, 23 Sep 2014 10:59:54 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from mailhub1.si.c-s.fr ([192.168.12.234]) by localhost (mailhub1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id uex_qIRupNNS; Tue, 23 Sep 2014 10:59:54 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id C00971C8505; Tue, 23 Sep 2014 10:59:54 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8A67CC73CB; Tue, 23 Sep 2014 10:59:54 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id PV77DaCJDW1p; Tue, 23 Sep 2014 10:59:54 +0200 (CEST) Received: from PO10863.localdomain (unknown [192.168.4.167]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 2DC95C73C8; Tue, 23 Sep 2014 10:59:53 +0200 (CEST) Received: by localhost.localdomain (Postfix, from userid 0) id 696B81AB26D; Tue, 23 Sep 2014 10:54:37 +0200 (CEST) From: Christophe Leroy To: "David S. Miller" CC: linux-kernel@vger.kernel.org, Eric Dumazet , netdev@vger.kernel.org Subject: [PATCH] net: optimise inet_proto_csum_replace4() Message-Id: <20140923085437.696B81AB26D@localhost.localdomain> Date: Tue, 23 Sep 2014 10:54:37 +0200 (CEST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org csum_partial() is a generic function which is not optimised for small fixed length calculations, and its use requires to store "from" and "to" values in memory while we already have them available in registers. This also has impact, especially on RISC processors. In the same spirit as the change done by Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() taking into account RFC1624. I spotted during a NATted tcp transfert that csum_partial() is one of top 5 consuming functions (around 8%), and the second user of csum_partial() is inet_proto_csum_replace4(). Signed-off-by: Christophe Leroy Acked-by: Eric Dumazet --- -- net/core/utils.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/net/core/utils.c b/net/core/utils.c index eed3433..efc76dd 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -306,16 +306,14 @@ EXPORT_SYMBOL(in6_pton); void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, __be32 from, __be32 to, int pseudohdr) { - __be32 diff[] = { ~from, to }; if (skb->ip_summed != CHECKSUM_PARTIAL) { - *sum = csum_fold(csum_partial(diff, sizeof(diff), - ~csum_unfold(*sum))); + *sum = csum_fold(csum_add(csum_sub(~csum_unfold(*sum), from), + to)); if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) - skb->csum = ~csum_partial(diff, sizeof(diff), - ~skb->csum); + skb->csum = ~csum_add(csum_sub(~(skb->csum), from), to); } else if (pseudohdr) - *sum = ~csum_fold(csum_partial(diff, sizeof(diff), - csum_unfold(*sum))); + *sum = ~csum_fold(csum_add(csum_sub(csum_unfold(*sum), from), + to)); } EXPORT_SYMBOL(inet_proto_csum_replace4);