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 A4BB9C433EF for ; Fri, 4 Feb 2022 04:32:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354164AbiBDEci (ORCPT ); Thu, 3 Feb 2022 23:32:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233571AbiBDEci (ORCPT ); Thu, 3 Feb 2022 23:32:38 -0500 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2DEBC061714 for ; Thu, 3 Feb 2022 20:32:37 -0800 (PST) Received: by mail-pl1-x62c.google.com with SMTP id z5so4117658plg.8 for ; Thu, 03 Feb 2022 20:32:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:subject:to:cc:message-id:in-reply-to:references :mime-version; bh=j3XulYOyxjt0H6Dm+T6h4fIFDcGa8dxAZc2gSXDaSOM=; b=W/zivjjoKcpfM4mLFy7M2wN6INoqQnQ9+THaeoyJplASvlVzpFvhUjWzghAnSVecht qxS/JdI8/sw3FW0MgfZPMXid6yWcWMn/aRywFmJw0dnJWC8rHYIZv3JfmHWpK5NfRFEv v6puWhdFkw9N6X49ZKOvjn7X/o7ki9PhGgsrZxb50pnKaL7oTOm5w+iDQxZ+5vmxoao3 Px8d7C+QCd0ZkWEm+Mooyur44U3OKHz92BBB0bfNHRNy5Ryi962t8qszsP2d4f+zRQqh 1ZlwBMP9yUAgaFACrgXh+oEwUFNZejcLTPiaPum6LhM/JBkliJ08H1gViRGDikH6VDwV jsUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:subject:to:cc:message-id:in-reply-to :references:mime-version; bh=j3XulYOyxjt0H6Dm+T6h4fIFDcGa8dxAZc2gSXDaSOM=; b=ReDgazD22TQNV7tnlTMBBwbIVTyS20FoxE2dWABnw0x01xG+RzBijiQ4h5b3ThUX0O 2VlQdWAZQsb46MqX7hcqokaWo4KHd7eLIGCTKnCYfl0Z4zLsJPLa5de3rWRtVB7yIDdY b1WYYbuhIrrV1ydQnqpD38QIFQgv4OnD5EUKd1yOEMPTIgeRvKymP2pBdScxLXS1qSDL 26rupDTV8vs0PEeAoTML7ZAgz6SezkSx0hR5CGv2XQAgnqhC13QEY8ABLNUG4MnM82Zc YzqioD57UgmEny2lRVLIRFUnhL0KCZc1e+lxRbRQsvZ+00Jmft78AcyNE7DkAlGzQgMA JCag== X-Gm-Message-State: AOAM533eBNaVPmGC7QVLhBvtDnB6mIY28NocwZEBjbHRl8O7+/9AoAkB WUD8JjTRgYRPlII6FtyHImlrh/TqFUo= X-Google-Smtp-Source: ABdhPJzv0bt3bTJi2ggiVDWq5kNjR2SHlSVotuslt9CrIVBByDtcpDgU0QKIB5P8Ge1jNioB76aXgw== X-Received: by 2002:a17:903:1d0:: with SMTP id e16mr1443116plh.65.1643949157210; Thu, 03 Feb 2022 20:32:37 -0800 (PST) Received: from [192.168.1.223] ([47.151.162.98]) by smtp.gmail.com with ESMTPSA id f12sm477953pgg.35.2022.02.03.20.32.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 20:32:36 -0800 (PST) Date: Thu, 03 Feb 2022 20:32:29 -0800 From: Benjamin Xiao Subject: Re: Still seeing high autodefrag IO with kernel 5.16.5 To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org Message-Id: <5AJR6R.7DWSX2SE14RN3@gmail.com> In-Reply-To: <88b6fe3e-8317-8070-cb27-0aee4dc72cfb@gmx.com> References: <9409dc0c-e99d-cc61-757e-727bd54c6ffd@gmx.com> <88b6fe3e-8317-8070-cb27-0aee4dc72cfb@gmx.com> X-Mailer: geary/40.0 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Okay, I just compiled a custom Arch kernel with your patches applied. Will test soon. Besides enabling autodefrag and redownloading a game from Steam, what other sorts of tests should I do? Ben On Fri, Feb 4 2022 at 09:54:19 AM +0800, Qu Wenruo wrote: > > > On 2022/2/4 09:17, Qu Wenruo wrote: >> >> >> On 2022/2/4 04:05, Benjamin Xiao wrote: >>> Hello all, >>> >>> Even after the defrag patches that landed in 5.16.5, I am still >>> seeing >>> lots of cpu usage and disk writes to my SSD when autodefrag is >>> enabled. >>> I kinda expected slightly more IO during writes compared to 5.15, >>> but >>> what I am actually seeing is massive amounts of btrfs-cleaner i/o >>> even >>> when no programs are actively writing to the disk. >>> >>> I can reproduce it quite reliably on my 2TB Btrfs Steam library >>> partition. In my case, I was downloading Strange Brigade, which is a >>> roughly 25GB download and 33.65GB on disk. Somewhere during the >>> download, iostat will start reporting disk writes around 300 MB/s, >>> even >>> though Steam itself reports disk usage of 40-45MB/s. After the >>> download >>> finishes and nothing else is being written to disk, I still see >>> around >>> 90-150MB/s worth of disk writes. Checking in iotop, I can see btrfs >>> cleaner and other btrfs processes writing a lot of data. >>> >>> I left it running for a while to see if it was just some maintenance >>> tasks that Btrfs needed to do, but it just kept going. I tried to >>> reboot, but it actually prevented me from properly rebooting. After >>> systemd timed out, my system finally shutdown. >>> >>> Here are my mount options: >>> rw,relatime,compress-force=zstd:2,ssd,autodefrag,space_cache=v2,subvolid=5,subvol=/ >>> >> >> Compression, I guess that's the reason. >> >> From the very beginning, btrfs defrag doesn't handle compressed >> extent >> well. >> >> Even if a compressed extent is already at its maximum capacity, btrfs >> will still try to defrag it. >> >> I believe the behavior is masked by other problems in older kernels >> thus >> not that obvious. >> >> But after rework of defrag in v5.16, this behavior is more exposed. > > And if possible, please try this diff on v5.15.x, and see if v5.15 is > really doing less IO than v5.16.x. > > The diff will solve a problem in the old code, where autodefrag is > almost not working. > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index cc61813213d8..f6f2468d4883 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -1524,13 +1524,8 @@ int btrfs_defrag_file(struct inode *inode, > struct > file *file, > continue; > } > > - if (!newer_than) { > - cluster = (PAGE_ALIGN(defrag_end) >> > - PAGE_SHIFT) - i; > - cluster = min(cluster, max_cluster); > - } else { > - cluster = max_cluster; > - } > + cluster = (PAGE_ALIGN(defrag_end) >> PAGE_SHIFT) - i; > + cluster = min(cluster, max_cluster); > > if (i + cluster > ra_index) { > ra_index = max(i, ra_index); > >> >> There are patches to address the compression related problem, but not >> yet merged: >> >> https://patchwork.kernel.org/project/linux-btrfs/list/?series=609387 >> >> Mind to test them to see if that's the case? >> >> Thanks, >> Qu >>> >>> >>> I've disabled autodefrag again for now to save my SSD, but just >>> wanted >>> to say that there is still an issue. Have the defrag issues been >>> fully >>> fixed or are there more patches incoming despite what Reddit and >>> Phoronix say? XD >>> >>> Thanks! >>> Ben >>> >>>