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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96E0CC433EF for ; Tue, 1 Mar 2022 15:06:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235521AbiCAPGm convert rfc822-to-8bit (ORCPT ); Tue, 1 Mar 2022 10:06:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232090AbiCAPGk (ORCPT ); Tue, 1 Mar 2022 10:06:40 -0500 Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA570A6468; Tue, 1 Mar 2022 07:05:58 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id B0E44609B3C0; Tue, 1 Mar 2022 16:05:55 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 0v40nSVbi-hE; Tue, 1 Mar 2022 16:05:55 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 33003609B3D3; Tue, 1 Mar 2022 16:05:55 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id Kz-2b_1qeBCK; Tue, 1 Mar 2022 16:05:55 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id F2CA5609B3C0; Tue, 1 Mar 2022 16:05:54 +0100 (CET) Date: Tue, 1 Mar 2022 16:05:54 +0100 (CET) From: Richard Weinberger To: Jan Kara Cc: wuchi zero , =?utf-8?Q?Rafa=C5=82_Mi=C5=82ecki?= , tj , mszeredi , sedat dilek , axboe , Andrew Morton , torvalds , linux-mm , linux-mtd , linux-fsdevel , linux-kernel Message-ID: <719960584.100772.1646147154879.JavaMail.zimbra@nod.at> In-Reply-To: <20220301103218.ulbmakdy4gbw2fso@quack3.lan> References: <2104629126.100059.1646129517209.JavaMail.zimbra@nod.at> <20220301103218.ulbmakdy4gbw2fso@quack3.lan> Subject: Re: Different writeback timing since v5.14 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF97 (Linux)/8.8.12_GA_3809) Thread-Topic: Different writeback timing since v5.14 Thread-Index: A7tsGqUsSQ3AY4M1uWfsU/0uR9rf+A== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jan, ----- Ursprüngliche Mail ----- > Von: "Jan Kara" >> Is this expected? >> Just want to make sure that the said commit didn't uncover an UBIFS issue. > > Yes, I think it is expected. Likely the background threshold for UBIFS bdi > is very small (probably UBIFS is not used much for writeback compared to > other filesystems). Previously, we just used wb_stat() which returned 0 > (PCP counter inexact value) and so background writeback didn't trigger. Now > we use wb_stat_sum() when threshold is small, get exact value of dirty > pages and decide to start background writeback. Thanks for the prompt reply! > The only thing is, whether it is really expected that the threshold for > UBIFS bdi is so small. You can check the values in > /sys/kernel/debug/bdi//stats. BdiDirtyThresh is indeed 0. BdiWriteback: 0 kB BdiReclaimable: 0 kB BdiDirtyThresh: 0 kB DirtyThresh: 772620 kB BackgroundThresh: 385836 kB BdiDirtied: 0 kB BdiWritten: 0 kB BdiWriteBandwidth: 102400 kBps b_dirty: 0 b_io: 0 b_more_io: 0 b_dirty_time: 0 bdi_list: 1 state: 1 Thanks, //richard