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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 EE233C2BA17 for ; Mon, 6 Apr 2020 18:13:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8CB120731 for ; Mon, 6 Apr 2020 18:13:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726659AbgDFSNm (ORCPT ); Mon, 6 Apr 2020 14:13:42 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:34057 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726520AbgDFSNm (ORCPT ); Mon, 6 Apr 2020 14:13:42 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R481e4;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=7;SR=0;TI=SMTPD_---0TuqA70k_1586196816; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TuqA70k_1586196816) by smtp.aliyun-inc.com(127.0.0.1); Tue, 07 Apr 2020 02:13:38 +0800 Subject: Re: [PATCHv2 2/8] khugepaged: Do not stop collapse if less than half PTEs are referenced To: "Kirill A. Shutemov" , akpm@linux-foundation.org, Andrea Arcangeli Cc: Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" References: <20200403112928.19742-1-kirill.shutemov@linux.intel.com> <20200403112928.19742-3-kirill.shutemov@linux.intel.com> From: Yang Shi Message-ID: <238a9a53-cf9b-7729-46f1-9b2a5e37571a@linux.alibaba.com> Date: Mon, 6 Apr 2020 11:13:35 -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: <20200403112928.19742-3-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 4/3/20 4:29 AM, Kirill A. Shutemov wrote: > __collapse_huge_page_swapin() check number of referenced PTE to decide > if the memory range is hot enough to justify swapin. > > The problem is that it stops collapse altogether if there's not enough > referenced pages, not only swappingin. > > Signed-off-by: Kirill A. Shutemov > Fixes: 0db501f7a34c ("mm, thp: convert from optimistic swapin collapsing to conservative") > Reviewed-by: Zi Yan > --- > mm/khugepaged.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Acked-by: Yang Shi > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 99bab7e4d05b..14d7afc90786 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -905,7 +905,8 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, > /* we only decide to swapin, if there is enough young ptes */ > if (referenced < HPAGE_PMD_NR/2) { > trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); > - return false; > + /* Do not block collapse, only skip swapping in */ > + return true; > } > vmf.pte = pte_offset_map(pmd, address); > for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE;