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 96671C4332F for ; Fri, 2 Dec 2022 10:22:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DAF956B0074; Fri, 2 Dec 2022 05:22:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D5DB36B0075; Fri, 2 Dec 2022 05:22:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C25A76B0078; Fri, 2 Dec 2022 05:22:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id AFCBF6B0074 for ; Fri, 2 Dec 2022 05:22:51 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 881A51C5DA9 for ; Fri, 2 Dec 2022 10:22:51 +0000 (UTC) X-FDA: 80196977742.18.A7EF4E6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf03.hostedemail.com (Postfix) with ESMTP id D943B2000A for ; Fri, 2 Dec 2022 10:22:50 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=none; spf=none (imf03.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669976571; 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; bh=Y9ZqNSTAAKpWCTRDltbyh9yaj6hQDR0ta/KGZMliVz4=; b=AEtMQL4rz7Fnz5C3FU3AEkYQdvSU2W40jrSFUFOSnn1+5pjkM4rxzNaXsSKofrq/ifXdqp hO0428VHZy2+ISpyoe7/JG7Sg8VUz+oniSLUaocntLIy+lEjvKsHXHbvysqabdyJ7CaNzM pXpK9RTzuCX4TeiFaLFtTFt1+yh6j4k= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669976571; a=rsa-sha256; cv=none; b=I997Qc+GqeQ2bYpjyUPOjfjYzk+cX0SZjKb3oAtAzltYdj/e8ZcpkPpMnne2ef6e2TlPx4 U61wQdkkGPp3bU+cIuZOjv+smzmKQrgPYWxSX+3CTVjRs2t1+CmQl7M7o35s2QoLP8cmMI AbulHGdH7jM6XQ5oy4NC2HMKx4pCPRU= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=none; spf=none (imf03.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none Received: by verein.lst.de (Postfix, from userid 2407) id D937167373; Fri, 2 Dec 2022 11:22:45 +0100 (CET) Date: Fri, 2 Dec 2022 11:22:45 +0100 From: Christoph Hellwig To: "Ritesh Harjani (IBM)" Cc: Christoph Hellwig , Namjae Jeon , Sungjong Seo , Jan Kara , OGAWA Hirofumi , Mikulas Patocka , Dave Kleikamp , Bob Copeland , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-karma-devel@lists.sourceforge.net, linux-mm@kvack.org Subject: Re: start removing writepage instances Message-ID: <20221202102245.GA17715@lst.de> References: <20221113162902.883850-1-hch@lst.de> <20221116183900.yzpcymelnnwppoh7@riteshh-domain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221116183900.yzpcymelnnwppoh7@riteshh-domain> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspam-User: X-Spamd-Result: default: False [0.18 / 9.00]; BAYES_HAM(-2.32)[96.84%]; SUSPICIOUS_RECIPS(1.50)[]; AUTH_NA(1.00)[]; RCVD_NO_TLS_LAST(0.10)[]; MIME_GOOD(-0.10)[text/plain]; R_SPF_NA(0.00)[no SPF record]; RCVD_COUNT_TWO(0.00)[2]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWELVE(0.00)[14]; TO_MATCH_ENVRCPT_SOME(0.00)[]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; TO_DN_SOME(0.00)[]; DMARC_NA(0.00)[lst.de]; TAGGED_RCPT(0.00)[]; ARC_NA(0.00)[] X-Stat-Signature: ex6ekchzc3eoe7yt8sq4swmaszatzjb9 X-Rspamd-Queue-Id: D943B2000A X-Rspamd-Server: rspam05 X-HE-Tag: 1669976570-401481 X-Bogosity: Ham, tests=bogofilter, spamicity=0.060196, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Nov 17, 2022 at 12:09:00AM +0530, Ritesh Harjani (IBM) wrote: > reclaim. Now IIUC from previous discussions [1][2][3], reclaims happens from > the tail end of the LRU list which could do an I/O of a single page while > an ongoing writeback was in progress of multiple pages. This disrupts the I/O > pattern to become more random in nature, compared to, if we would have let > writeback/flusher do it's job of writing back dirty pages. Yes. > Also many filesystems behave very differently within their ->writepage calls, > e.g. ext4 doesn't actually write in ->writepage for DELAYED blocks. I don't think it's many file systems. As far as I can tell only ext4 actually is significantly different. > 2. Now the other place from where ->writepage can be called from is, writeout() > function, which is a fallback function for migration (fallback_migrate_folio()). > fallback_migrate_folio() is called from move_to_new_folio() if ->migrate_folio > is not defined for the FS. Also there is generic_writepages and folio_write_one/write_one_page. > Is above a correct understanding? Yes.