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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 4E145C433E0 for ; Fri, 26 Mar 2021 09:45:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E79A761A57 for ; Fri, 26 Mar 2021 09:45:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229915AbhCZJp1 (ORCPT ); Fri, 26 Mar 2021 05:45:27 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:33753 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229573AbhCZJpC (ORCPT ); Fri, 26 Mar 2021 05:45:02 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xlpang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UTMseJh_1616751899; Received: from localhost(mailfrom:xlpang@linux.alibaba.com fp:SMTPD_---0UTMseJh_1616751899) by smtp.aliyun-inc.com(127.0.0.1); Fri, 26 Mar 2021 17:44:59 +0800 From: Xunlei Pang To: Andrew Morton , Alexander Duyck , Mel Gorman Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Xunlei Pang Subject: [PATCH 3/4] mm/page_reporting: Introduce "page_reporting_factor=" boot parameter Date: Fri, 26 Mar 2021 17:44:57 +0800 Message-Id: <1616751898-58393-4-git-send-email-xlpang@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1616751898-58393-1-git-send-email-xlpang@linux.alibaba.com> References: <1616751898-58393-1-git-send-email-xlpang@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently the default behaviour(value 100) is to do full report, although we can control it after boot via "page_reporting_factor" sysfs knob, it could still be late because some amount of memory has already been reported before operating this knob. Sometimes we really want it safely off by default and turn it on as needed at runtime, so "page_reporting_factor=" boot parameter is that guarantee and meets different default setting requirements. There's also a real-world problem that I noticed on tiny instances, it always reports some memory at boot stage before application starts and uses up memory which retriggers EPT fault after boot. The following data(right after boot) indicates that 172032KiB pages were unnecessarily reported and refault in: $ cat /sys/kernel/mm/page_reporting/refault_kbytes 172032 $ cat /sys/kernel/mm/page_reporting/reported_kbytes 0 Thus it's reasonable to turn the page reporting off by default and enable it at runtime as needed. Signed-off-by: Xunlei Pang --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ mm/page_reporting.c | 13 +++++++++++++ 2 files changed, 16 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 0454572..46e296c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3524,6 +3524,9 @@ off: turn off poisoning (default) on: turn on poisoning + page_reporting_factor= [KNL] Guest Free Page Reporting percentile. + [0, 100]: 0 - off, not report; 100 - default, full report. + panic= [KNL] Kernel behaviour on panic: delay timeout > 0: seconds before rebooting timeout = 0: wait forever diff --git a/mm/page_reporting.c b/mm/page_reporting.c index 86c6479..6ffedb8 100644 --- a/mm/page_reporting.c +++ b/mm/page_reporting.c @@ -524,3 +524,16 @@ static int __init page_reporting_init(void) } module_init(page_reporting_init); + +static int __init setup_reporting_factor(char *str) +{ + int v; + + if (kstrtoint(str, 10, &v)) + return -EINVAL; + if (v >= 0 && v <= 100) + reporting_factor = v; + + return 0; +} +__setup("page_reporting_factor=", setup_reporting_factor); -- 1.8.3.1