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 10237CCA480 for ; Wed, 20 Jul 2022 06:04:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 55C4D6B0072; Wed, 20 Jul 2022 02:04:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E2EF6B0073; Wed, 20 Jul 2022 02:04:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3831A6B0074; Wed, 20 Jul 2022 02:04:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 2440D6B0072 for ; Wed, 20 Jul 2022 02:04:57 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id F127CA047D for ; Wed, 20 Jul 2022 06:04:56 +0000 (UTC) X-FDA: 79706439792.26.F091A1B Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf13.hostedemail.com (Postfix) with ESMTP id 49B1220011 for ; Wed, 20 Jul 2022 06:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=opw3pkg9MKPmz9HBHhoEOSCX/4fVSd9GJbKVFnBB1bQ=; b=009wHgCqWpQKNwVR2UBJag0ovx 4wvkFS9R+0dytc8DHeTt2ztFC+qO4DpdY3U9uOVt0nZknhJCInJxtvKLwWEHPGaZrGNbO22CqUpGK Xx71Je8WNSViMlYX0rPxlSePYOhvYlaIsz43DEs59fyOHs1CEpW1/93j3julJislhwRmvNjUa0eEg Oj0XnpLjCg/sDSJ7qSGEfIkgDOPMWUcAZ/q7pzSlZrPXiecgjQoGOKcgj9/BqYnmaJHwiO6fk1WI/ MKQC5SpI7WzmODclNMFFw4zIuLgKy0A2j3cSILNNy+dSkcwni8pT4o1lwvNa0yL8j7nswsgE1tvXv PPrREAGg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oE2p2-000u6T-VI; Wed, 20 Jul 2022 06:04:36 +0000 Date: Tue, 19 Jul 2022 23:04:36 -0700 From: Christoph Hellwig To: CGEL Cc: Matthew Wilcox , 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> <62d79a79.1c69fb81.e4cba.37f5@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <62d79a79.1c69fb81.e4cba.37f5@mx.google.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=009wHgCq; dmarc=none; spf=none (imf13.hostedemail.com: domain of BATV+59bb276a4702f876c99d+6905+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+59bb276a4702f876c99d+6905+infradead.org+hch@bombadil.srs.infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658297095; 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=opw3pkg9MKPmz9HBHhoEOSCX/4fVSd9GJbKVFnBB1bQ=; b=XwXx8dOR3VhU0pYrtg7tsmrE7NbywjtvPrC3p4FnAyTcqRUCJHgg6aKIFrHJovj6EHf81P IJgM92PThIRzQTX8pP7gOsmYPNgX8rgNLwnHgcbBkoyUk3oaZKvRHL9zreHnbYOq442wyK Zto2Cwa5y0nS8vIVj8nerpWkz0jWlUQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658297095; a=rsa-sha256; cv=none; b=6Gu1AgrPhv7RmC0p2oo/i4GlGjH/VQw1T7YWdLCfv4NrSrUFmLsgjRACs68PLVPGllhRCG A6maNQ+fa72zatpaRAE0uUqUoCmR5oStTzlb7vGTBE6Y5cx6k8W/7gRSLsgNPen9Ve2YiX L5hZ92f8RoTCv2xEJWd3q/PYoECPcpU= X-Rspamd-Queue-Id: 49B1220011 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=009wHgCq; dmarc=none; spf=none (imf13.hostedemail.com: domain of BATV+59bb276a4702f876c99d+6905+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+59bb276a4702f876c99d+6905+infradead.org+hch@bombadil.srs.infradead.org X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 4ixj83aqf9xmbg64dpa8kg3qruihbg4t X-HE-Tag: 1658297094-8350 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 06:02:32AM +0000, CGEL wrote: > For example, some systems will create a lot of pagecache when boot up > while reading bzImage, ramdisk, docker images etc. Most of this pagecache > is useless after boot up. It may has a longterm negative effects for the > workload when trigger page reclaim. It is especially harmful when trigger > direct_reclaim or we need allocate pages in atomic context. So users may > chose to drop_caches after boot up. It is purely a debug interface. If you want to drop specific page cache that needs to be done through madvise.