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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY 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 38CA6C10F06 for ; Thu, 28 Mar 2019 21:59:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 040912075E for ; Thu, 28 Mar 2019 21:59:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728041AbfC1V7i (ORCPT ); Thu, 28 Mar 2019 17:59:38 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:48115 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728029AbfC1V7i (ORCPT ); Thu, 28 Mar 2019 17:59:38 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R611e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04452;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0TNtCAaw_1553810371; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TNtCAaw_1553810371) by smtp.aliyun-inc.com(127.0.0.1); Fri, 29 Mar 2019 05:59:35 +0800 Subject: Re: [PATCH 06/10] mm: vmscan: demote anon DRAM pages to PMEM node To: Keith Busch Cc: "mhocko@suse.com" , "mgorman@techsingularity.net" , "riel@surriel.com" , "hannes@cmpxchg.org" , "akpm@linux-foundation.org" , "Hansen, Dave" , "Busch, Keith" , "Williams, Dan J" , "Wu, Fengguang" , "Du, Fan" , "Huang, Ying" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" References: <1553316275-21985-1-git-send-email-yang.shi@linux.alibaba.com> <1553316275-21985-7-git-send-email-yang.shi@linux.alibaba.com> <20190324222040.GE31194@localhost.localdomain> <20190327003541.GE4328@localhost.localdomain> <39d8fb56-df60-9382-9b47-59081d823c3c@linux.alibaba.com> <20190327130822.GD7389@localhost.localdomain> From: Yang Shi Message-ID: <599849e6-05b6-1e4d-7578-5cf8825963d2@linux.alibaba.com> Date: Thu, 28 Mar 2019 14:59:30 -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: <20190327130822.GD7389@localhost.localdomain> 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 3/27/19 6:08 AM, Keith Busch wrote: > On Tue, Mar 26, 2019 at 08:41:15PM -0700, Yang Shi wrote: >> On 3/26/19 5:35 PM, Keith Busch wrote: >>> migration nodes have higher free capacity than source nodes. And since >>> your attempting THP's without ever splitting them, that also requires >>> lower fragmentation for a successful migration. >> Yes, it is possible. However, migrate_pages() already has logic to >> handle such case. If the target node has not enough space for migrating >> THP in a whole, it would split THP then retry with base pages. > Oh, you're right, my mistake on splitting. So you have a good best effort > migrate, but I still think it can fail for legitimate reasons that should > have a swap fallback. Yes, it still could fail. I can't tell which way is better for now. I just thought scanning another round then migrating should be still faster than swapping off the top of my head. Thanks, Yang