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 04DEDC28B2B for ; Fri, 19 Aug 2022 02:48:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245308AbiHSCsF (ORCPT ); Thu, 18 Aug 2022 22:48:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240319AbiHSCsD (ORCPT ); Thu, 18 Aug 2022 22:48:03 -0400 Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA3E2CCE01 for ; Thu, 18 Aug 2022 19:48:01 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0VMe73D-_1660877278; Received: from 30.240.99.21(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0VMe73D-_1660877278) by smtp.aliyun-inc.com; Fri, 19 Aug 2022 10:47:59 +0800 Message-ID: Date: Fri, 19 Aug 2022 10:47:58 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.1.0 Subject: Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func To: SeongJae Park Cc: akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220819022850.52236-1-sj@kernel.org> From: haoxin In-Reply-To: <20220819022850.52236-1-sj@kernel.org> 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 在 2022/8/19 上午10:28, SeongJae Park 写道: > Hi Xin, > >> 在 2022/8/19 上午1:11, SeongJae Park 写道: >>> Hi Xin, >>> >>> >>> On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao wrote: >>> >>>> In damon_lru_sort_apply_parameters(), if "monitor_region_start" >>>> and "monitor_region_end" is not a valid physical address range, >>>> There no need to run the remainder codes in it. >>> The function, 'damon_lru_sort_apply_parameters()', checks validity of >>> parameters and construct the DAMON context one by one. For example, >>> 'damon_set_attrs()' returns an error if the parameters are invalid. So the >>> intended flow is, >>> >>> 1. check DAMON attributes parameters, >>> 2. apply DAMON attributes parameters, >>> 3. check scheme parameters, >>> 4. apply scheme parameters, >>> 5. check target region parameters, and >>> 6. apply target region parameters. >>> >>> Therefore what this patch does is making the target regions validity check to >>> be done earlier than validity checks of other parameters. There is no special >>> reason to check the region earlier than others. Also, this change makes the >>> flow of the function a little bit weird in my humble opinion, as the flow will >>> be >>> >>> 1. check target region parameters, >>> 2. check DAMON attributes parameters, >>> 3. apply DAMON attributes parameters, >>> 4. check scheme parameters, >>> 5. apply scheme parameters, and >>> 6. apply target region parameters. >> Ok, understand what you mean, my fix looks ugly, buy any apply above >> are not not necessary if one of them checks failed, why not check all >> fisrt and then apply them, like this: >> >> 1. check target region parameters, >> >> 2. check DAMON attributes parameters, >> >> 3. check scheme parameters, > The parameter values could be changed by users after the check, so we should > cache those somewhere anyway. In other words, we cache those in the DAMON > context. Therefore I think the above works were not totally waste of the time. > Also, because the parameters applying functions like 'damon_set_attrs()' does > the check and applying of the parameters together, I feel like current flow is > natural. Ok,  Thank you for your detailed  explain, just keep it. but there still a problem in damon_lru_sort_apply_parameters if (!monitor_region_start && !monitor_region_end && !get_monitoring_region(&monitor_region_start, &monitor_region_end)) if (!monitor_region_start || !monitor_region_end || !get_monitoring_region(&monitor_region_start, &monitor_region_end)) the '&&' should fix to '||', anyone checks fail, it should return ? >