From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B67E2C43460 for ; Wed, 12 May 2021 14:43:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79A0D613BF for ; Wed, 12 May 2021 14:43:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231402AbhELOoz (ORCPT ); Wed, 12 May 2021 10:44:55 -0400 Received: from pegase2.c-s.fr ([93.17.235.10]:53807 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231380AbhELOoy (ORCPT ); Wed, 12 May 2021 10:44:54 -0400 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4FgHbh5mDJz9sdw; Wed, 12 May 2021 16:43:44 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id XhpERfMAMcjt; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4FgHbh4nsRz9sdc; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 83D6C8B7F4; Wed, 12 May 2021 16:43:44 +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 KNm8b5FGVtrW; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 10B2E8B7F3; Wed, 12 May 2021 16:43:44 +0200 (CEST) Subject: Re: [PATCH] powerpc: Force inlining of csum_add() To: Segher Boessenkool Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20210511105154.GJ10366@gate.crashing.org> <20210512143105.GW10366@gate.crashing.org> From: Christophe Leroy Message-ID: <2623fe98-7a73-f7a2-bcba-2d668d00ffd0@csgroup.eu> Date: Wed, 12 May 2021 16:43:33 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210512143105.GW10366@gate.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 12/05/2021 à 16:31, Segher Boessenkool a écrit : > On Wed, May 12, 2021 at 02:56:56PM +0200, Christophe Leroy wrote: >> Le 11/05/2021 à 12:51, Segher Boessenkool a écrit : >>> Something seems to have decided this asm is more expensive than it is. >>> That isn't always avoidable -- the compiler cannot look inside asms -- >>> but it seems it could be improved here. >>> >>> Do you have (or can make) a self-contained testcase? >> >> I have not tried, and I fear it might be difficult, because on a kernel >> build with dozens of calls to csum_add(), only ip6_tunnel.o exhibits such >> an issue. > > Yeah. Sometimes you can force some of the decisions, but that usually > requires knowing too many GCC internals :-/ > >>>> And there is even one completely unused instance of csum_add(). >>> >>> That is strange, that should never happen. >> >> It seems that several .o include unused versions of csum_add. After the >> final link, one remains (in addition to the used one) in vmlinux. > > But it is a static function, so it should not end up in any object file > where it isn't used. Well .... did I dream ? Now I only find one extra .o with unused csum_add() : That's net/ipv6/exthdrs.o It matches the one found in vmlinux. Are you interested in -fdump-tree-einline-all for that one as well ? Christophe From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC6D5C433B4 for ; Wed, 12 May 2021 14:44:13 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E9148613BD for ; Wed, 12 May 2021 14:44:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9148613BD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FgHcC26W7z30Bq for ; Thu, 13 May 2021 00:44:11 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FgHbq0HHrz2xv1 for ; Thu, 13 May 2021 00:43:48 +1000 (AEST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4FgHbh5mDJz9sdw; Wed, 12 May 2021 16:43:44 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id XhpERfMAMcjt; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4FgHbh4nsRz9sdc; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 83D6C8B7F4; Wed, 12 May 2021 16:43:44 +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 KNm8b5FGVtrW; Wed, 12 May 2021 16:43:44 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 10B2E8B7F3; Wed, 12 May 2021 16:43:44 +0200 (CEST) Subject: Re: [PATCH] powerpc: Force inlining of csum_add() To: Segher Boessenkool References: <20210511105154.GJ10366@gate.crashing.org> <20210512143105.GW10366@gate.crashing.org> From: Christophe Leroy Message-ID: <2623fe98-7a73-f7a2-bcba-2d668d00ffd0@csgroup.eu> Date: Wed, 12 May 2021 16:43:33 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210512143105.GW10366@gate.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 12/05/2021 à 16:31, Segher Boessenkool a écrit : > On Wed, May 12, 2021 at 02:56:56PM +0200, Christophe Leroy wrote: >> Le 11/05/2021 à 12:51, Segher Boessenkool a écrit : >>> Something seems to have decided this asm is more expensive than it is. >>> That isn't always avoidable -- the compiler cannot look inside asms -- >>> but it seems it could be improved here. >>> >>> Do you have (or can make) a self-contained testcase? >> >> I have not tried, and I fear it might be difficult, because on a kernel >> build with dozens of calls to csum_add(), only ip6_tunnel.o exhibits such >> an issue. > > Yeah. Sometimes you can force some of the decisions, but that usually > requires knowing too many GCC internals :-/ > >>>> And there is even one completely unused instance of csum_add(). >>> >>> That is strange, that should never happen. >> >> It seems that several .o include unused versions of csum_add. After the >> final link, one remains (in addition to the used one) in vmlinux. > > But it is a static function, so it should not end up in any object file > where it isn't used. Well .... did I dream ? Now I only find one extra .o with unused csum_add() : That's net/ipv6/exthdrs.o It matches the one found in vmlinux. Are you interested in -fdump-tree-einline-all for that one as well ? Christophe