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=-10.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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=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 27E4BC4363D for ; Mon, 5 Oct 2020 12:16:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0FF42085B for ; Mon, 5 Oct 2020 12:16:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="L93tfTb5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726578AbgJEMQ3 (ORCPT ); Mon, 5 Oct 2020 08:16:29 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:53096 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725994AbgJEMQ3 (ORCPT ); Mon, 5 Oct 2020 08:16:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601900187; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I+9FWa50a4fAVSLereFH2OCTk21D3ec5peVlRys8eQY=; b=L93tfTb5hE1Q1Hhv28B+zxkwkWLgydRno2LUFKpM7WBiPdf1sSVtY6AiLsj2Y6rAjq9JTu tuHYa7jy6WroLdJ32azOj6UAxXtm9jScsNJvI0OjzYfZZEJy1WxAt+6gDOpUcfuMbXvp/o pKRaWeGJcMUiGYaReFUoBQquUJIpdHE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-547-TlvT2dKcMy2qnf7NNmOSuA-1; Mon, 05 Oct 2020 08:16:25 -0400 X-MC-Unique: TlvT2dKcMy2qnf7NNmOSuA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C5087107ACF5; Mon, 5 Oct 2020 12:16:22 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-222.ams2.redhat.com [10.36.114.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8AAF6271A3; Mon, 5 Oct 2020 12:16:13 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, Andrew Morton , Matthew Wilcox , David Hildenbrand , Oscar Salvador , Pankaj Gupta , Wei Yang , Alexander Duyck , Mel Gorman , Michal Hocko , Dave Hansen , Vlastimil Babka , Mike Rapoport , Scott Cheloha , Michael Ellerman Subject: [PATCH v2 3/5] mm/page_alloc: move pages to tail in move_to_free_list() Date: Mon, 5 Oct 2020 14:15:32 +0200 Message-Id: <20201005121534.15649-4-david@redhat.com> In-Reply-To: <20201005121534.15649-1-david@redhat.com> References: <20201005121534.15649-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org 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 --- 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