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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 14201C07EBF for ; Fri, 18 Jan 2019 17:54:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7FD420850 for ; Fri, 18 Jan 2019 17:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729012AbfARRym (ORCPT ); Fri, 18 Jan 2019 12:54:42 -0500 Received: from outbound-smtp08.blacknight.com ([46.22.139.13]:41757 "EHLO outbound-smtp08.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728574AbfARRym (ORCPT ); Fri, 18 Jan 2019 12:54:42 -0500 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp08.blacknight.com (Postfix) with ESMTPS id EF0A11C3080 for ; Fri, 18 Jan 2019 17:54:39 +0000 (GMT) Received: (qmail 6988 invoked from network); 18 Jan 2019 17:54:39 -0000 Received: from unknown (HELO stampy.163woodhaven.lan) (mgorman@techsingularity.net@[37.228.229.96]) by 81.17.254.9 with ESMTPA; 18 Jan 2019 17:54:39 -0000 From: Mel Gorman To: Andrew Morton Cc: David Rientjes , Andrea Arcangeli , Vlastimil Babka , Linux List Kernel Mailing , Linux-MM , Mel Gorman Subject: [PATCH 17/22] mm, compaction: Do not consider a need to reschedule as contention Date: Fri, 18 Jan 2019 17:51:31 +0000 Message-Id: <20190118175136.31341-18-mgorman@techsingularity.net> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190118175136.31341-1-mgorman@techsingularity.net> References: <20190118175136.31341-1-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Scanning on large machines can take a considerable length of time and eventually need to be rescheduled. This is treated as an abort event but that's not appropriate as the attempt is likely to be retried after making numerous checks and taking another cycle through the page allocator. This patch will check the need to reschedule if necessary but continue the scanning. The main benefit is reduced scanning when compaction is taking a long time or the machine is over-saturated. It also avoids an unnecessary exit of compaction that ends up being retried by the page allocator in the outer loop. 5.0.0-rc1 5.0.0-rc1 synccached-v3r16 noresched-v3r17 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 2958.27 ( 0.00%) 2965.68 ( -0.25%) Amean fault-both-5 4091.90 ( 0.00%) 3995.90 ( 2.35%) Amean fault-both-7 5803.05 ( 0.00%) 5842.12 ( -0.67%) Amean fault-both-12 9481.06 ( 0.00%) 9550.87 ( -0.74%) Amean fault-both-18 14141.51 ( 0.00%) 13304.72 ( 5.92%) Amean fault-both-24 16438.00 ( 0.00%) 14618.59 ( 11.07%) Amean fault-both-30 17531.72 ( 0.00%) 16650.96 ( 5.02%) Amean fault-both-32 17101.96 ( 0.00%) 17145.15 ( -0.25%) Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka --- mm/compaction.c | 23 ++++------------------- 1 file changed, 4 insertions(+), 19 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 9aa71945255d..293d9a9e6f00 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -404,21 +404,6 @@ static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags, return true; } -/* - * Aside from avoiding lock contention, compaction also periodically checks - * need_resched() and records async compaction as contended if necessary. - */ -static inline void compact_check_resched(struct compact_control *cc) -{ - /* async compaction aborts if contended */ - if (need_resched()) { - if (cc->mode == MIGRATE_ASYNC) - cc->contended = true; - - cond_resched(); - } -} - /* * Compaction requires the taking of some coarse locks that are potentially * very heavily contended. The lock should be periodically unlocked to avoid @@ -447,7 +432,7 @@ static bool compact_unlock_should_abort(spinlock_t *lock, return true; } - compact_check_resched(cc); + cond_resched(); return false; } @@ -736,7 +721,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, return 0; } - compact_check_resched(cc); + cond_resched(); if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC)) { skip_on_failure = true; @@ -1370,7 +1355,7 @@ static void isolate_freepages(struct compact_control *cc) * suitable migration targets, so periodically check resched. */ if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))) - compact_check_resched(cc); + cond_resched(); page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, zone); @@ -1664,7 +1649,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, * need to schedule. */ if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))) - compact_check_resched(cc); + cond_resched(); page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, zone); -- 2.16.4