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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7C5FFC07E9C for ; Wed, 7 Jul 2021 09:13:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DB4461CC2 for ; Wed, 7 Jul 2021 09:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231271AbhGGJPl (ORCPT ); Wed, 7 Jul 2021 05:15:41 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:54618 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231144AbhGGJPj (ORCPT ); Wed, 7 Jul 2021 05:15:39 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id CC2AA225C9; Wed, 7 Jul 2021 09:12:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1625649178; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JoKp/ueTWTvINDzusVwgf6ql4EB0CbzpyJO64PWxFeU=; b=OnDAjMxETxRzwi5mlwAecuiQGm4eHjTJLy8SrG59l1aU5rbVFCrc+VpJiVH3QiFH/KNE1m FfciId9+Iwm6J5RgWkXnch3U5wxFHNAAnro2ejqRN2u3sDjNw/gaMKmvLRriSc+3oZRO16 R7XRfpY8UhOfYmS+K2YHKDvjeo16lgg= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id A4880A3B9A; Wed, 7 Jul 2021 09:12:58 +0000 (UTC) Date: Wed, 7 Jul 2021 11:12:57 +0200 From: Michal Hocko To: Ohhoon Kwon Cc: david@redhat.com, akpm@linux-foundation.org, bhe@redhat.com, rppt@linux.ibm.com, ohkwon1043@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/3] mm: sparse: pass section_nr to section_mark_present Message-ID: References: <20210705085538.14557-1-ohoono.kwon@samsung.com> <20210705085538.14557-2-ohoono.kwon@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210705085538.14557-2-ohoono.kwon@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 05-07-21 17:55:36, Ohhoon Kwon wrote: > With CONFIG_SPARSEMEM_EXTREME enabled, __section_nr() which converts > mem_section to section_nr could be costly since it iterates all > section roots to check if the given mem_section is in its range. > > On the other hand, __nr_to_section() which converts section_nr to > mem_section can be done in O(1). > > Let's pass section_nr instead of mem_section ptr to > section_mark_present() in order to reduce needless iterations. > > Signed-off-by: Ohhoon Kwon > Acked-by: Michal Hocko > Acked-by: Mike Rapoport > Reviewed-by: David Hildenbrand > --- > mm/sparse.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 6326cdf36c4f..b4fae2fc6276 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -187,13 +187,14 @@ void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn, > * those loops early. > */ > unsigned long __highest_present_section_nr; > -static void section_mark_present(struct mem_section *ms) > +static void section_mark_present(unsigned long section_nr) > { > - unsigned long section_nr = __section_nr(ms); > + struct mem_section *ms; > > if (section_nr > __highest_present_section_nr) > __highest_present_section_nr = section_nr; > > + ms = __nr_to_section(section_nr); > ms->section_mem_map |= SECTION_MARKED_PRESENT; Can you add the ms parameter here so that we get rid of the pointless __nr_to_section as suggested in the previous review feedback? -- Michal Hocko SUSE Labs