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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 9C748C35DE1 for ; Tue, 25 Feb 2020 14:15:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 740EA218AC for ; Tue, 25 Feb 2020 14:15:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730639AbgBYOPm (ORCPT ); Tue, 25 Feb 2020 09:15:42 -0500 Received: from outbound-smtp24.blacknight.com ([81.17.249.192]:36838 "EHLO outbound-smtp24.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729411AbgBYOPi (ORCPT ); Tue, 25 Feb 2020 09:15:38 -0500 Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp24.blacknight.com (Postfix) with ESMTPS id 6B8ADC0ACD for ; Tue, 25 Feb 2020 14:15:36 +0000 (GMT) Received: (qmail 1897 invoked from network); 25 Feb 2020 14:15:36 -0000 Received: from unknown (HELO stampy.112glenside.lan) (mgorman@techsingularity.net@[84.203.18.57]) by 81.17.254.9 with ESMTPA; 25 Feb 2020 14:15:36 -0000 From: Mel Gorman To: Andrew Morton Cc: Michal Hocko , Vlastimil Babka , Ivan Babrou , Rik van Riel , Linux-MM , Linux Kernel Mailing List , Mel Gorman Subject: [PATCH 1/3] mm, page_alloc: Disable boosted watermark based reclaim on low-memory systems Date: Tue, 25 Feb 2020 14:15:32 +0000 Message-Id: <20200225141534.5044-2-mgorman@techsingularity.net> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20200225141534.5044-1-mgorman@techsingularity.net> References: <20200225141534.5044-1-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org An off-list bug report indicated that watermark boosting was affecting a very small memory system and causing excessive reclaim. Watermark boosting is intended to reduce the mixing of page mobility types within pageblocks for high-order allocations. If the system has so little memory that pages are not even grouped by mobility, then watermark boosting should also be disabled. Signed-off-by: Mel Gorman --- mm/internal.h | 6 +++++- mm/page_alloc.c | 6 ++++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 3cf20ab3ca01..439561cc90d9 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -534,10 +534,14 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, #endif #define ALLOC_KSWAPD 0x200 /* allow waking of kswapd */ +static inline void disable_watermark_boosting(void) +{ + watermark_boost_factor = 0; +} + enum ttu_flags; struct tlbflush_unmap_batch; - /* * only for MM internal work items which do not depend on * any allocations or locks which might depend on allocations diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3c4eb750a199..c5c05b6dc459 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5810,10 +5810,12 @@ void __ref build_all_zonelists(pg_data_t *pgdat) * made on memory-hotadd so a system can start with mobility * disabled and enable it later */ - if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES)) + if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES)) { page_group_by_mobility_disabled = 1; - else + disable_watermark_boosting(); + } else { page_group_by_mobility_disabled = 0; + } pr_info("Built %u zonelists, mobility grouping %s. Total pages: %ld\n", nr_online_nodes, -- 2.16.4