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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 3D8F0C0018C for ; Mon, 7 Dec 2020 11:26:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFAC623356 for ; Mon, 7 Dec 2020 11:26:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726832AbgLGL0R (ORCPT ); Mon, 7 Dec 2020 06:26:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:51324 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726788AbgLGL0P (ORCPT ); Mon, 7 Dec 2020 06:26:15 -0500 Date: Mon, 7 Dec 2020 11:25:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607340335; bh=tCa+SCe7Tz2pY32ACYBN1TqZqetx06uBL1NMCeLWUZ4=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=LO1t2k18IowPpv2iCVCBshWRF1a4vzde4KtMgs8ydGWAtuVF3pf1r2hNBS+BeFIOI 6Nh2gDTQ5J+29/yVnmVEgLy3lXoGzzozXzjdPoZ8QnP9bx1xeAoA5hKi+yY0qv/0QZ PLos+SmCTZMcDWZLWYs74X0zGOpNAGG2IkxNmV7TFOe8coW0M3f/J9SUBOoZUmgLlk MFYmpYwZ3qqk2vUX78qY9TyScLj3mJKqGujU4XKLUo7gK20qG6Rs/8JJUz/N7aO+KN 3z6QgfEaIz+bNzqqs9L6qQPc8VmUkYiCgO6emc8xdpVOGkCTVB6lh4a2tu/rPU2Y1g gC0NEAeaU65Wg== From: Will Deacon To: Yury Norov Cc: Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] arm64: enable GENERIC_FIND_FIRST_BIT Message-ID: <20201207112530.GB4379@willie-the-truck> References: <20201205165406.108990-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201205165406.108990-1-yury.norov@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 05, 2020 at 08:54:06AM -0800, Yury Norov wrote: > ARM64 doesn't implement find_first_{zero}_bit in arch code and doesn't > enable it in config. It leads to using find_next_bit() which is less > efficient: [...] > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 1515f6f153a0..2b90ef1f548e 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -106,6 +106,7 @@ config ARM64 > select GENERIC_CPU_AUTOPROBE > select GENERIC_CPU_VULNERABILITIES > select GENERIC_EARLY_IOREMAP > + select GENERIC_FIND_FIRST_BIT Does this actually make any measurable difference? The disassembly with or without this is _very_ similar for me (clang 11). Will 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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 D7D4EC4361B for ; Mon, 7 Dec 2020 11:26:37 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 85B802310B for ; Mon, 7 Dec 2020 11:26:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 85B802310B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DoTeHNy9Cn5ieN/JwCvYr1Q+POw27vJhp9+nW6EaW6w=; b=gjfuqhL4SYhMXTDCNMSHf/PPP LsdGCUVdUppUZGtcvHXZQmbrTfEAIEjuPAjIF8uov3pF38gRtWxsjTc6pDtMCrhjGa/o3uhRTYP3L en1x4fC61TfcebAHo2LbTZcGAgz06Csb9Pjv+5Z0Y2uw2X5uTfLWX10r3Lqhmz9j0sMd/UaUgmLZJ DHlf3zJ5rqgFSDvYxb6S9cD5cyXdoU8JFxWbwmwfRYZOY6AjRc5zWCUB8eXiNP8MZCVvbUheQy7I9 URNE0i9A8dybmwIjF8ALdVrmXPfqPtxsGdScj4rACxVW4sAEQsenJnQLqnq6eEUexeJUPaXvPvK6a N2Q5Jof2Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmEeA-00005R-WF; Mon, 07 Dec 2020 11:25:39 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmEe8-00004x-Ad for linux-arm-kernel@lists.infradead.org; Mon, 07 Dec 2020 11:25:37 +0000 Date: Mon, 7 Dec 2020 11:25:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607340335; bh=tCa+SCe7Tz2pY32ACYBN1TqZqetx06uBL1NMCeLWUZ4=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=LO1t2k18IowPpv2iCVCBshWRF1a4vzde4KtMgs8ydGWAtuVF3pf1r2hNBS+BeFIOI 6Nh2gDTQ5J+29/yVnmVEgLy3lXoGzzozXzjdPoZ8QnP9bx1xeAoA5hKi+yY0qv/0QZ PLos+SmCTZMcDWZLWYs74X0zGOpNAGG2IkxNmV7TFOe8coW0M3f/J9SUBOoZUmgLlk MFYmpYwZ3qqk2vUX78qY9TyScLj3mJKqGujU4XKLUo7gK20qG6Rs/8JJUz/N7aO+KN 3z6QgfEaIz+bNzqqs9L6qQPc8VmUkYiCgO6emc8xdpVOGkCTVB6lh4a2tu/rPU2Y1g gC0NEAeaU65Wg== From: Will Deacon To: Yury Norov Subject: Re: [PATCH] arm64: enable GENERIC_FIND_FIRST_BIT Message-ID: <20201207112530.GB4379@willie-the-truck> References: <20201205165406.108990-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201205165406.108990-1-yury.norov@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201207_062536_606335_500472F4 X-CRM114-Status: GOOD ( 10.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Catalin Marinas , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, Dec 05, 2020 at 08:54:06AM -0800, Yury Norov wrote: > ARM64 doesn't implement find_first_{zero}_bit in arch code and doesn't > enable it in config. It leads to using find_next_bit() which is less > efficient: [...] > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 1515f6f153a0..2b90ef1f548e 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -106,6 +106,7 @@ config ARM64 > select GENERIC_CPU_AUTOPROBE > select GENERIC_CPU_VULNERABILITIES > select GENERIC_EARLY_IOREMAP > + select GENERIC_FIND_FIRST_BIT Does this actually make any measurable difference? The disassembly with or without this is _very_ similar for me (clang 11). Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel