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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFA97C433EF for ; Tue, 31 May 2022 02:55:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2EBE16B0074; Mon, 30 May 2022 22:55:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 29E5A6B0078; Mon, 30 May 2022 22:55:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 187676B007D; Mon, 30 May 2022 22:55:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 02EEA6B0074 for ; Mon, 30 May 2022 22:55:28 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id C1142801BE for ; Tue, 31 May 2022 02:55:27 +0000 (UTC) X-FDA: 79524522294.16.1ABC5BE Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf11.hostedemail.com (Postfix) with ESMTP id 5B6424004E for ; Tue, 31 May 2022 02:55:18 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LBxdW6NSLzQkNx; Tue, 31 May 2022 10:52:15 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 31 May 2022 10:55:20 +0800 Subject: Re: [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics To: Andrew Morton CC: , References: <20220527092626.31883-1-linmiaohe@huawei.com> <20220527092626.31883-3-linmiaohe@huawei.com> <20220530160409.c9b17085adb6112d8580f37d@linux-foundation.org> From: Miaohe Lin Message-ID: Date: Tue, 31 May 2022 10:55:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220530160409.c9b17085adb6112d8580f37d@linux-foundation.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf11.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5B6424004E X-Stat-Signature: cdpjn3wa1j3p8c1egenadqe51ajurju1 X-Rspam-User: X-HE-Tag: 1653965718-621041 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/5/31 7:04, Andrew Morton wrote: > On Fri, 27 May 2022 17:26:25 +0800 Miaohe Lin wrote: > >> At swapoff time, we're going to swap in the pages continuously. So calling >> lookup_swap_cache would confuse statistics. We should use find_get_page >> directly here. > > Why is the existing behaviour wrong? swapoff() has to swap stuff in to > be able to release the swap device. Why do you believe that this > swapin activity should not be accounted? IMHO, statistics, e.g. swap_cache_info.find_success, are used to show the effectiveness of the swap cache activity. So they should only reflect the memory accessing activity of the user. I think swapoff can't reflect the effectiveness of the swap cache activity because it just swaps in pages one by one. Or statistics should reflect all the activity of the user including swapoff? Thanks! > > > . >