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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D8AAFC4727E for ; Tue, 6 Oct 2020 12:12:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4557B20760 for ; Tue, 6 Oct 2020 12:12:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="PfznraKz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4557B20760 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A5A7F6B006C; Tue, 6 Oct 2020 08:12:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A0C4F6B006E; Tue, 6 Oct 2020 08:12:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8FA256B0070; Tue, 6 Oct 2020 08:12:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0146.hostedemail.com [216.40.44.146]) by kanga.kvack.org (Postfix) with ESMTP id 605E86B006C for ; Tue, 6 Oct 2020 08:12:29 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id DEC573635 for ; Tue, 6 Oct 2020 12:12:28 +0000 (UTC) X-FDA: 77341388376.15.wall86_440c1ca271c6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id 9AA711814B0C9 for ; Tue, 6 Oct 2020 12:12:28 +0000 (UTC) X-HE-Tag: wall86_440c1ca271c6 X-Filterd-Recvd-Size: 6671 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Tue, 6 Oct 2020 12:12:27 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601986346; h=from:from:reply-to:subject:subject: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=mAU57Ek0qHw3pvzhn1nGqMRGEvP+BHT9YA55QmaOE0c=; b=PfznraKzbDoQ+43ul+fCEC6Ow3fb+GPiDyy0YheRdIEd5y093LGzF7+HryEbkAFwWyjGkf 3zKDdTUHNT8nvpwqTgFG24rVLdFSOubG2Rg7qJL6FAxG7SZPG47/y6+D3GDFw0LRMABnKQ ReFcS00OGqBMBevTFcg7tcZbt8VllnQ= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B8F2FAB95; Tue, 6 Oct 2020 12:12:26 +0000 (UTC) Date: Tue, 6 Oct 2020 14:12:24 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, Andrew Morton , Matthew Wilcox , Oscar Salvador , Pankaj Gupta , Wei Yang , Alexander Duyck , Mel Gorman , Dave Hansen , Vlastimil Babka , Mike Rapoport , Scott Cheloha , Michael Ellerman Subject: Re: [PATCH v2 3/5] mm/page_alloc: move pages to tail in move_to_free_list() Message-ID: <20201006121224.GE29020@dhcp22.suse.cz> References: <20201005121534.15649-1-david@redhat.com> <20201005121534.15649-4-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201005121534.15649-4-david@redhat.com> 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 05-10-20 14:15:32, David Hildenbrand wrote: > Whenever we move pages between freelists via move_to_free_list()/ > move_freepages_block(), we don't actually touch the pages: > 1. Page isolation doesn't actually touch the pages, it simply isolates > pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist. > When undoing isolation, we move the pages back to the target list. > 2. Page stealing (steal_suitable_fallback()) moves free pages directly > between lists without touching them. > 3. reserve_highatomic_pageblock()/unreserve_highatomic_pageblock() moves > free pages directly between freelists without touching them. > > We already place pages to the tail of the freelists when undoing isolation > via __putback_isolated_page(), let's do it in any case (e.g., if order <= > pageblock_order) and document the behavior. To simplify, let's move the > pages to the tail for all move_to_free_list()/move_freepages_block() users. > > In 2., the target list is empty, so there should be no change. In 3., > we might observe a change, however, highatomic is more concerned about > allocations succeeding than cache hotness - if we ever realize this > change degrades a workload, we can special-case this instance and add a > proper comment. > > This change results in all pages getting onlined via online_pages() to > be placed to the tail of the freelist. > > Reviewed-by: Oscar Salvador > Acked-by: Pankaj Gupta > Reviewed-by: Wei Yang > Cc: Andrew Morton > Cc: Alexander Duyck > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Dave Hansen > Cc: Vlastimil Babka > Cc: Wei Yang > Cc: Oscar Salvador > Cc: Mike Rapoport > Cc: Scott Cheloha > Cc: Michael Ellerman > Signed-off-by: David Hildenbrand Much simpler! Acked-by: Michal Hocko Thanks! > --- > mm/page_alloc.c | 10 +++++++--- > mm/page_isolation.c | 5 +++++ > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index df5ff0cd6df1..b187e46cf640 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -901,13 +901,17 @@ static inline void add_to_free_list_tail(struct page *page, struct zone *zone, > area->nr_free++; > } > > -/* Used for pages which are on another list */ > +/* > + * Used for pages which are on another list. Move the pages to the tail > + * of the list - so the moved pages won't immediately be considered for > + * allocation again (e.g., optimization for memory onlining). > + */ > static inline void move_to_free_list(struct page *page, struct zone *zone, > unsigned int order, int migratetype) > { > struct free_area *area = &zone->free_area[order]; > > - list_move(&page->lru, &area->free_list[migratetype]); > + list_move_tail(&page->lru, &area->free_list[migratetype]); > } > > static inline void del_page_from_free_list(struct page *page, struct zone *zone, > @@ -2340,7 +2344,7 @@ static inline struct page *__rmqueue_cma_fallback(struct zone *zone, > #endif > > /* > - * Move the free pages in a range to the free lists of the requested type. > + * Move the free pages in a range to the freelist tail of the requested type. > * Note that start_page and end_pages are not aligned on a pageblock > * boundary. If alignment is required, use move_freepages_block() > */ > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index abfe26ad59fd..83692b937784 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -106,6 +106,11 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) > * If we isolate freepage with more than pageblock_order, there > * should be no freepage in the range, so we could avoid costly > * pageblock scanning for freepage moving. > + * > + * We didn't actually touch any of the isolated pages, so place them > + * to the tail of the freelist. This is an optimization for memory > + * onlining - just onlined memory won't immediately be considered for > + * allocation. > */ > if (!isolated_page) { > nr_pages = move_freepages_block(zone, page, migratetype, NULL); > -- > 2.26.2 -- Michal Hocko SUSE Labs