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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C89D8C3815B for ; Wed, 15 Apr 2020 20:32:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0B3420787 for ; Wed, 15 Apr 2020 20:32:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S371250AbgDOUcj (ORCPT ); Wed, 15 Apr 2020 16:32:39 -0400 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:46249 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2636948AbgDOUcH (ORCPT ); Wed, 15 Apr 2020 16:32:07 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0TvdyiWI_1586982722; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TvdyiWI_1586982722) by smtp.aliyun-inc.com(127.0.0.1); Thu, 16 Apr 2020 04:32:04 +0800 Subject: Re: [PATCHv3, RESEND 3/8] khugepaged: Drain all LRU caches before scanning pages To: "Kirill A. Shutemov" , akpm@linux-foundation.org, Andrea Arcangeli Cc: Zi Yan , Ralph Campbell , John Hubbard , William Kucharski , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200413125220.663-1-kirill.shutemov@linux.intel.com> <20200413125220.663-4-kirill.shutemov@linux.intel.com> From: Yang Shi Message-ID: <63b9ce4d-0e1d-8e40-5ec3-154fe6e95557@linux.alibaba.com> Date: Wed, 15 Apr 2020 13:31:58 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20200413125220.663-4-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/13/20 5:52 AM, Kirill A. Shutemov wrote: > Having a page in LRU add cache offsets page refcount and gives > false-negative on PageLRU(). It reduces collapse success rate. > > Drain all LRU add caches before scanning. It happens relatively > rare and should not disturb the system too much. > > Signed-off-by: Kirill A. Shutemov > --- > mm/khugepaged.c | 2 ++ > 1 file changed, 2 insertions(+) Acked-by: Yang Shi > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 5968ec5ddd6b..ee66c140c2d6 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2059,6 +2059,8 @@ static void khugepaged_do_scan(void) > > barrier(); /* write khugepaged_pages_to_scan to local stack */ > > + lru_add_drain_all(); > + > while (progress < pages) { > if (!khugepaged_prealloc_page(&hpage, &wait)) > break;