Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30154C433EF for ; Thu, 23 Dec 2021 01:00:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239988AbhLWBA0 (ORCPT ); Wed, 22 Dec 2021 20:00:26 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:36489 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238387AbhLWBAX (ORCPT ); Wed, 22 Dec 2021 20:00:23 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R671e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0V.TB1Hv_1640221220; Received: from 30.21.164.23(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0V.TB1Hv_1640221220) by smtp.aliyun-inc.com(127.0.0.1); Thu, 23 Dec 2021 09:00:21 +0800 Message-ID: <362fb4fe-34c8-d83d-b8be-a4140e19b244@linux.alibaba.com> Date: Thu, 23 Dec 2021 09:01:05 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 0/2] Add a new scheme to support demotion on tiered memory system To: Andrew Morton Cc: sj@kernel.org, ying.huang@intel.com, dave.hansen@linux.intel.com, ziy@nvidia.com, shy828301@gmail.com, zhongjiang-ali@linux.alibaba.com, xlpang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20211222160105.a267eaacefae77ae094c050e@linux-foundation.org> From: Baolin Wang In-Reply-To: <20211222160105.a267eaacefae77ae094c050e@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/23/2021 8:01 AM, Andrew Morton wrote: > On Wed, 22 Dec 2021 19:14:39 +0800 Baolin Wang wrote: > >> Now on tiered memory system with different memory types, the reclaim path in >> shrink_page_list() already support demoting pages to slow memory node instead >> of discarding the pages. However, at that time the fast memory node memory >> wartermark is already tense, which will increase the memory allocation latency >> during page demotion. So a new method from user space demoting cold pages >> proactively will be more helpful. >> >> We can rely on the DAMON in user space to help to monitor the cold memory on >> fast memory node, and demote the cold pages to slow memory node proactively to >> keep the fast memory node in a healthy state. >> >> This patch set introduces a new scheme named DAMOS_DEMOTE to support this feature, >> and works well from my testing. Any comments are welcome. Thanks. > > This is interesting. > > I think it would be helpful if we could have some example scenarios in > this changelog, help people understand how to use DAMOS_DEMOTE and what > effects it has. Sure. > > Documentation/admin-guide/mm/damon/usage.rst would like an update? Ah, I missed updating de Doc, and will do in v3. > And the DAMON user space tool? Yes. Thanks for your comments.