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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06BA7C433EF for ; Fri, 18 Mar 2022 05:13:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232483AbiCRFOn (ORCPT ); Fri, 18 Mar 2022 01:14:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232469AbiCRFOg (ORCPT ); Fri, 18 Mar 2022 01:14:36 -0400 Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08F802719 for ; Thu, 17 Mar 2022 22:13:17 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R471e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0V7UWWcn_1647580393; Received: from B-X3VXMD6M-2058.local(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0V7UWWcn_1647580393) by smtp.aliyun-inc.com(127.0.0.1); Fri, 18 Mar 2022 13:13:14 +0800 From: xhao@linux.alibaba.com Reply-To: xhao@linux.alibaba.com Subject: Re: [RFC PATCH V1 0/3] mm/damon: Add CMA minotor support To: David Hildenbrand , sj@kernel.org Cc: rongwei.wang@linux.alibaba.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Baolin Wang , SeongJae Park References: <6e6ef9fa-3916-3449-954d-efd63a959019@linux.alibaba.com> Message-ID: <611f2ec6-04de-440a-3d54-c2bc34f45cf3@linux.alibaba.com> Date: Fri, 18 Mar 2022 13:13:12 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/18/22 12:42 AM, David Hildenbrand wrote: > On 17.03.22 08:03, Xin Hao wrote: >> Hi David, >> >> On 3/16/22 11:09 PM, David Hildenbrand wrote: >>> On 15.03.22 17:37, Xin Hao wrote: >>> >>> s/minotor/monitor/ >> Thanks,  i will fix it. >>>> The purpose of these patches is to add CMA memory monitoring function. >>>> In some memory tight scenarios, it will be a good choice to release more >>>> memory by monitoring the CMA memory. >>> I'm sorry, but it's hard to figure out what the target use case should >>> be. Who will release CMA memory and how? Who will monitor that? What are >>> the "some memory tight scenarios"? What's the overall design goal? >> I may not be describing exactly what  i mean，My intention is to find out >> how much of the reserved CMA space is actually used and which is unused, >> For those that are not used, I understand that they can be released by >> cma_release(). Of course, This is just a little personal thought that I >> think is helpful for saving memory. > Hm, not quite. We can place movable allocations on cma areas, to be > migrated away once required for allocations via CMA. So just looking at > the pages allocated within a CMA area doesn't really tell you what's > actually going on. I don't think so,  the damon not looking at the pages allocate, It is constantly monitoring who is using CMA area pages through tracking page access bit in the kernel via the kdamond.x thread, So through damon, it can tell us about  the hot and cold distribution of CMA memory. --cc  SeongJae Park More about damon, you can refer to this link：https://sjp38.github.io/post/damon/ > -- Best Regards! Xin Hao