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 46324C43334 for ; Wed, 20 Jul 2022 03:03:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DA0DA6B0073; Tue, 19 Jul 2022 23:03:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D50BB6B0074; Tue, 19 Jul 2022 23:03:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C40506B0078; Tue, 19 Jul 2022 23:03:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B55416B0073 for ; Tue, 19 Jul 2022 23:03:22 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 33EA51A0444 for ; Wed, 20 Jul 2022 03:03:22 +0000 (UTC) X-FDA: 79705982244.15.C969BE0 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf16.hostedemail.com (Postfix) with ESMTP id DEF1E1800A1 for ; Wed, 20 Jul 2022 03:03:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=YW9vZ0DFmjEUcrU3kVkIJzmwjJ6l61hPGiZtfLK4BoM=; b=NAFWsobF+Pu6BHXFPXmayLBdzj xRgKGEDrNxOylkaL24UcgMTm5X7LleQLZ0h7gaOU4qPoQChCKUuI4VSBVv3gDyaDnTYQ2AxMMsZW3 mxjV1cgUYT+wGU2JJiDal5KUDbI8+Mo5EHAv3RHRdt2FzcXtDepe9716G2kkOK0cTU8ilOuaiuEIz f4HRTtWYSLHWlDL0GwkM8AkNqfeEjqIhGkiunFn/ICh6didUrQ//71KDAdzncRgGD66bVrvvBEsu+ GKgTmuSjzyZ3O3Vk93wrfA1raDI4RDLdPcBwxfghAScD/FjerrmzQi9LasfJlJUHbhfycik36y19Q ydpd9dAA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oDzyy-00E6Vz-QC; Wed, 20 Jul 2022 03:02:40 +0000 Date: Wed, 20 Jul 2022 04:02:40 +0100 From: Matthew Wilcox To: cgel.zte@gmail.com Cc: viro@zeniv.linux.org.uk, hughd@google.com, akpm@linux-foundation.org, hch@infradead.org, hsiangkao@linux.alibaba.com, yang.yang29@zte.com.cn, axboe@kernel.dk, yangerkun@huawei.com, johannes.thumshirn@wdc.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ran Xiaokai Subject: Re: [PATCH] fs: drop_caches: skip dropping pagecache which is always dirty Message-ID: References: <20220720022118.1495752-1-yang.yang29@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220720022118.1495752-1-yang.yang29@zte.com.cn> ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=NAFWsobF; dmarc=none; spf=none (imf16.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658286201; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=YW9vZ0DFmjEUcrU3kVkIJzmwjJ6l61hPGiZtfLK4BoM=; b=7mjs/X5deD6/qv3wOM5D7u+Kj8nuTp/eGAqB17Bld0ahqGS0nLxTV7cb9jrCPyUZU3pQB2 Y+8RKt1jnkCwF93pAzb4hMlbWV0wIaY8Ox/01GqpT40vGFYW5795h1bOjkloYGoyrtJdWn Cd4LYz8k/pf4P62oewopSFsyAwJbino= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658286201; a=rsa-sha256; cv=none; b=6H4JFv+ZNQHz1YNTClGgD36w8mGcpArhOS7khKiRWw/LDFsmSvDJl75coIHVsTci2756P2 7te8P+JxAtc52cTTbuRaqsLpfyj4100sLOvsaStE7u5HsUGEAgJDqFSSGUBAP0oDlrwf3d zYnCW0/B3QxsYcNNRiuRzVtdxTcJzA4= X-Stat-Signature: ncjo8reiyyt97xm4kbq8brxs369ydhun X-Rspamd-Queue-Id: DEF1E1800A1 X-Rspam-User: Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=NAFWsobF; dmarc=none; spf=none (imf16.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam11 X-HE-Tag: 1658286200-99382 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 Wed, Jul 20, 2022 at 02:21:19AM +0000, cgel.zte@gmail.com wrote: > From: Yang Yang > > Pagecache of some kind of fs has PG_dirty bit set once it was > allocated, so it can't be dropped. These fs include ramfs and > tmpfs. This can make drop_pagecache_sb() more efficient. Why do we want to make drop_pagecache_sb() more efficient?