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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,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 4ADC2C43387 for ; Fri, 4 Jan 2019 12:50:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 203C6208E3 for ; Fri, 4 Jan 2019 12:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727790AbfADMuZ (ORCPT ); Fri, 4 Jan 2019 07:50:25 -0500 Received: from outbound-smtp08.blacknight.com ([46.22.139.13]:42643 "EHLO outbound-smtp08.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbfADMuZ (ORCPT ); Fri, 4 Jan 2019 07:50:25 -0500 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp08.blacknight.com (Postfix) with ESMTPS id 3E35C1C2154 for ; Fri, 4 Jan 2019 12:50:22 +0000 (GMT) Received: (qmail 28816 invoked from network); 4 Jan 2019 12:50:22 -0000 Received: from unknown (HELO stampy.163woodhaven.lan) (mgorman@techsingularity.net@[37.228.229.96]) by 81.17.254.9 with ESMTPA; 4 Jan 2019 12:50:22 -0000 From: Mel Gorman To: Linux-MM Cc: David Rientjes , Andrea Arcangeli , Vlastimil Babka , ying.huang@intel.com, kirill@shutemov.name, Andrew Morton , Linux List Kernel Mailing , Mel Gorman Subject: [PATCH 00/25] Increase success rates and reduce latency of compaction v2 Date: Fri, 4 Jan 2019 12:49:46 +0000 Message-Id: <20190104125011.16071-1-mgorman@techsingularity.net> X-Mailer: git-send-email 2.16.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This series reduces scan rates and success rates of compaction, primarily by using the free lists to shorten scans, better controlling of skip information and whether multiple scanners can target the same block and capturing pageblocks before being stolen by parallel requests. The series is based on the 4.21/5.0 merge window after Andrew's tree had been merged. It's known to rebase cleanly. Primarily I'm using thpscale to measure the impact of the series. The benchmark creates a large file, maps it, faults it, punches holes in the mapping so that the virtual address space is fragmented and then tries to allocate THP. It re-executes for different numbers of threads. From a fragmentation perspective, the workload is relatively benign but it does stress compaction. The overall impact on latencies for a 1-socket machine is baseline patches Amean fault-both-3 5362.80 ( 0.00%) 4446.89 * 17.08%* Amean fault-both-5 9488.75 ( 0.00%) 5660.86 * 40.34%* Amean fault-both-7 11909.86 ( 0.00%) 8549.63 * 28.21%* Amean fault-both-12 16185.09 ( 0.00%) 11508.36 * 28.90%* Amean fault-both-18 12057.72 ( 0.00%) 19013.48 * -57.69%* Amean fault-both-24 23939.95 ( 0.00%) 19676.16 * 17.81%* Amean fault-both-30 26606.14 ( 0.00%) 27363.23 ( -2.85%) Amean fault-both-32 31677.12 ( 0.00%) 23154.09 * 26.91%* While there is a glitch at the 18-thread mark, it's known that the base page allocation latency was much lower and huge pages were taking longer -- partially due a high allocation success rate. The allocation success rates are much improved baseline patches Percentage huge-3 70.93 ( 0.00%) 98.30 ( 38.60%) Percentage huge-5 56.02 ( 0.00%) 83.36 ( 48.81%) Percentage huge-7 60.98 ( 0.00%) 89.04 ( 46.01%) Percentage huge-12 73.02 ( 0.00%) 94.36 ( 29.23%) Percentage huge-18 94.37 ( 0.00%) 95.87 ( 1.58%) Percentage huge-24 84.95 ( 0.00%) 97.41 ( 14.67%) Percentage huge-30 83.63 ( 0.00%) 96.69 ( 15.62%) Percentage huge-32 81.69 ( 0.00%) 96.10 ( 17.65%) That's a nearly perfect allocation success rate. The biggest impact is on the scan rates Compaction migrate scanned 106520811 26934599 Compaction free scanned 4180735040 26584944 The number of pages scanned for migration was reduced by 74% and the free scanner was reduced by 99.36%. So much less work in exchange for lower latency and better success rates. The series was also evaluated using a workload that heavily fragments memory but the benefits there are also significant, albeit not presented. It was commented that we should be rethinking scanning entirely and to a large extent I agree. However, to achieve that you need a lot of this series in place first so it's best to make the linear scanners as best as possible before ripping them out. include/linux/compaction.h | 3 +- include/linux/gfp.h | 7 +- include/linux/mmzone.h | 2 + include/linux/sched.h | 4 + kernel/sched/core.c | 3 + mm/compaction.c | 1031 ++++++++++++++++++++++++++++++++++---------- mm/internal.h | 23 +- mm/migrate.c | 2 +- mm/page_alloc.c | 70 ++- 9 files changed, 908 insertions(+), 237 deletions(-) -- 2.16.4