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=-8.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 57614C432BE for ; Mon, 30 Aug 2021 14:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3650260E90 for ; Mon, 30 Aug 2021 14:34:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237081AbhH3Ofi (ORCPT ); Mon, 30 Aug 2021 10:35:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231757AbhH3Ofe (ORCPT ); Mon, 30 Aug 2021 10:35:34 -0400 Received: from bombadil.infradead.org (unknown [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1965CC061575 for ; Mon, 30 Aug 2021 07:34:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:To: Subject:Sender:Reply-To:Cc:Content-ID:Content-Description; bh=mkGTDPNkt+i0u372UDIl+CX0pOwINf5R8IDtgqkrmm0=; b=vgwD7dHvsWoj01UZg923MZmsZt PUbyVQXfMg/kqJQoJTx8IiThC7uvXXkphmhXniJZrfKzzu4F6Inp1D2JNqgPJHqMm7wWEm5ETrDkB /aGyADDagiejrbResWNqbXOgSBIlto+2EHPu+pHKqu1QMpebuDQcTsvJq49ptpJvJ0008pDQvuBp3 nPENZcU8O+jBLR/YJYk4jMdFNZFeRDTJn1jhp+hvI8TTsaXFXQEy3WmzQ+DvKg1CVTD6sfk1xWE7x QteADdy4RPLHd/q4CfQ8RR1BA5Ol+h9wmehE9InWd2IkGQWSdesMN8N9xUaT7EBXVIoysOGLd5JBa aKZasuFQ==; Received: from [2601:1c0:6280:3f0::aa0b] by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mKiMw-00HS00-Jh; Mon, 30 Aug 2021 14:34:38 +0000 Subject: Re: Why is Shmem included in Cached in /proc/meminfo? To: Mikko Rantalainen , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <5a42eb2b-fd7b-6296-f5d6-619661ad1418@peda.net> From: Randy Dunlap Message-ID: <0d11f620-0562-e150-259d-85de8d10cd7a@infradead.org> Date: Mon, 30 Aug 2021 07:34:38 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <5a42eb2b-fd7b-6296-f5d6-619661ad1418@peda.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [add linux-mm mailing list] On 8/30/21 12:44 AM, Mikko Rantalainen wrote: > It's not immediately obvious from fs/proc/meminfo.c function > meminfo_proc_show() but the output of Cached: field seems to always > include all of Shmem: field, too. > > Is this intentional? Usually cache is something that can be discarded if > needed but shared memory (e.g. used to contain files in tmpfs) cannot be > discarded without a data-loss. As such, I'd argue that it shouldn't be > included in the Cached: output. > > A simple fix could be > > - cached = global_node_page_state(NR_FILE_PAGES) - > - total_swapcache_pages() - i.bufferram; > + cached = global_node_page_state(NR_FILE_PAGES) - > + total_swapcache_pages() > + - i.bufferram - i.sharedram; > -- ~Randy