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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 150ECC4332D for ; Sat, 21 Mar 2020 03:04:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BC93E20709 for ; Sat, 21 Mar 2020 03:04:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="dfmMYfuO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC93E20709 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 689276B0003; Fri, 20 Mar 2020 23:04:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6391B6B0005; Fri, 20 Mar 2020 23:04:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 54F6F6B0007; Fri, 20 Mar 2020 23:04:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0187.hostedemail.com [216.40.44.187]) by kanga.kvack.org (Postfix) with ESMTP id 393556B0003 for ; Fri, 20 Mar 2020 23:04:23 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D8D28247F for ; Sat, 21 Mar 2020 03:04:22 +0000 (UTC) X-FDA: 76617875964.17.smash42_7d8326cf12741 X-HE-Tag: smash42_7d8326cf12741 X-Filterd-Recvd-Size: 2949 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Sat, 21 Mar 2020 03:04:22 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7622820663; Sat, 21 Mar 2020 03:04:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584759861; bh=wD2NFElW4kNMjyqEQuf/GpIMAXoft7zXObZHCXLTSx4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dfmMYfuOgzuK7l8NSSR392wSTcYhZHHNQdnX2Ksl4ydUK/vFdHLWu1vNdAzTvN4V5 22XyX4OUiN9EcU71pKCSH2tY7WxkHmTeO2pLC02rJV0y7tHBwXVn1Ae5TSUUtoVp68 aRsnet1zD3CSdqj/m7x1UQ7TXVsVHezg6ft8W6sc= Date: Fri, 20 Mar 2020 20:04:20 -0700 From: Andrew Morton To: qiwuchen55@gmail.com Cc: linux-mm@kvack.org, chenqiwu Subject: Re: [RESEND PATCH] mm/sparse: remove duplicated pfn_to_section_nr() Message-Id: <20200320200420.63d04e1fe92a642493e77cef@linux-foundation.org> In-Reply-To: <1584345587-16769-1-git-send-email-qiwuchen55@gmail.com> References: <1584345587-16769-1-git-send-email-qiwuchen55@gmail.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 16 Mar 2020 15:59:47 +0800 qiwuchen55@gmail.com wrote: > From: chenqiwu > > Remove duplicated pfn_to_section_nr() in pfn_valid() and pfn_present() > to increase executing efficiency of code. > > ... > > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1358,10 +1358,11 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) > static inline int pfn_valid(unsigned long pfn) > { > struct mem_section *ms; > + unsigned long sec_nr = pfn_to_section_nr(pfn); > > - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > + if (sec_nr >= NR_MEM_SECTIONS) > return 0; > - ms = __nr_to_section(pfn_to_section_nr(pfn)); > + ms = __nr_to_section(sec_nr); > if (!valid_section(ms)) > return 0; > /* > @@ -1374,9 +1375,11 @@ static inline int pfn_valid(unsigned long pfn) > > static inline int pfn_present(unsigned long pfn) > { > - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > + unsigned long sec_nr = pfn_to_section_nr(pfn); > + > + if (sec_nr >= NR_MEM_SECTIONS) > return 0; > - return present_section(__nr_to_section(pfn_to_section_nr(pfn))); > + return present_section(__nr_to_section(sec_nr)); > } > The compiler already makes this optimization (pfn_to_section_nr() is very simple). Generated code appears to be identical. I guess this patch could be sold as a cleanup, but I don't think it's worthwhile, really.