From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com [209.85.167.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC48D1BD501 for ; Tue, 6 Aug 2024 10:23:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722939830; cv=none; b=Z8Ro2m0a+tNBFqE+E4Rvl9h3CHhNjzWWoxnXlT3lpzzcJHgIc/0Iz3hj2YL4/I5S4xQebQPhB3dnVaROM73XVMol7gVYX7zvjP43+iP4RC26ZxHmYd1V6taYlnUc7qAPJ07aZleA29INamp3LWtQ06y2lEzhGw4cgktA6eTQ80Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722939830; c=relaxed/simple; bh=1r54Rx+4bFkHj40dedbCdi/YLRjBUZAJjP81wVdLCoA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=p91lYpCsPDGinWdcgL2fJWx7xOhc1E3xzSUAdU2jrqyVaKQZ6uo6Xmlw+HPSQOiglHN4+pT/oHchak1NLCtFhchStg98Lxze1uK7oXeaJxv/9Gl+9zUaOrOaTngtJ/uF/kql4Uaxm1kAf8WuDISxfgkA8mLpsFmVi4eKQl2Jjz4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JKgksuVN; arc=none smtp.client-ip=209.85.167.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JKgksuVN" Received: by mail-lf1-f43.google.com with SMTP id 2adb3069b0e04-530ad969360so701490e87.0 for ; Tue, 06 Aug 2024 03:23:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1722939827; x=1723544627; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:mime-version:date:message-id:sender:from:to :cc:subject:date:message-id:reply-to; bh=1r54Rx+4bFkHj40dedbCdi/YLRjBUZAJjP81wVdLCoA=; b=JKgksuVNu09rSk/3gJ1QpAKlhGnCDKmqswez++ltSLO+i6twRS20r4SaIuIZ2Rfo3G rvVLhKb8x26Uu2vzp0fXFv4igzZXPPb1JnyP4ybDxMf+akPO4XMePYHjKkv4n9VUQ5Sf ZRstj+AvGXRYkjVzyiWrbh3fI1C5Qi49g9fit8RYgpoCmiYJp30dVjpqPKxa8+NSL7Dk aG/4fvJp0URfJy3ZvG7UsqS7Rt2N7Wra7QHtw3AZzAQxj0V7bC6+SYdaBviv/KVvZuIL Ca5ejpO4f6XI4FK8wlngKumIcHm6chvdK0yqndBz1ea+VAyK+l5p/ae677tHO7ZMta4B 25lQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722939827; x=1723544627; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:mime-version:date:message-id:sender :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1r54Rx+4bFkHj40dedbCdi/YLRjBUZAJjP81wVdLCoA=; b=vosGIWTWkzYor5d6eY7E+wqwlFyqXAxeJ8/c7BHm9YKAvLtEktiAP48yfziM4HKJPR 95yNKqE81uYVz+mRnvKkRPnBclUykre+LhuKrbhvdmaYorszLdrR8lpK0fpd4ononN5p Ju3Kh89KKeGSIH5wXwbZz8YuLLE0wjNd7JsIC8A8mlpUDopH5Me7ntNEdBM5eAcSuSqH 4EEOgF5ibRFrkC36cGY78KDw1No+rDDxOPVONU9XG2PjRdDPbIzv2QUf5qfBrEfSJtFM IdPa8zVdizPCJaj1VqvF5TbpIlBKpiYR7hnnqcs9cDxrcUOuSARAQPb9dmL1690Hdt7l nCXg== X-Forwarded-Encrypted: i=1; AJvYcCUd4u9IegBWU03s+IhQPv5K7wu0aLMn/B3pBLJwZ+A1rPooqD7c5ihCQ1EepwIZRsYmF2M+47+/QBZurNT81qjYYLBQH1ITOnyTnBA= X-Gm-Message-State: AOJu0YxRG5NR+gYervTM18Q4Z4rFs6yuU4Elwa1QsXsbua+59/SEo+fB EnCTJyiDWmANKZLNDUuAJEsBgy2dobxIMwkrb5Hs48tUMTfxMb0F9gUUNg== X-Google-Smtp-Source: AGHT+IFzRQ0sFD5QjJ2NlPs2qnGkK3R8/nnH9Ir7PV4WL2Pp3e+r7y8q9Cq+/DyyE/NBiFv8a1nBeQ== X-Received: by 2002:a05:6512:239e:b0:530:ae22:a6f0 with SMTP id 2adb3069b0e04-530bb3929c7mr10910877e87.5.1722939826180; Tue, 06 Aug 2024 03:23:46 -0700 (PDT) Received: from 127.0.0.1 ([94.41.86.134]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-530bba2a0a5sm1405340e87.163.2024.08.06.03.23.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 06 Aug 2024 03:23:45 -0700 (PDT) Sender: Message-ID: <62433c69-5d07-4781-bf2f-6558d7e79134@gmail.com> Date: Tue, 6 Aug 2024 10:23:45 +0000 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: 'btrfs filesystem defragment' makes files explode in size, especially fallocated ones To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <7a85ea4e-814f-4940-bd3e-13299197530f@gmx.com> <90dab7d5-0ab8-48fe-8993-f821aa8a0db8@gmail.com> <0f6cc8e0-ab32-4792-863e-0ef795258051@gmx.com> <837fb96f-989c-4b56-8bd4-6f8fb5e60e7d@gmail.com> Content-Language: en-US From: Hanabishi In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/6/24 09:55, Qu Wenruo wrote: > So either there is something like cgroup involved (which can limits the > dirty page cache and trigger write backs), or some other weird > behavior/bugs. Yes, this line reveals something. I do have modified dirty page cache values. I tend to keep it on low values. Now playing around with it - yes, it is seems to be the cause. When I tune 'vm.dirty_ratio' and 'vm.dirty_background_ratio' up to higher values, the problem becames less prevalent. Which means lowering them cranks up the problem to extremes. E.g. try # sysctl -w vm.dirty_bytes=8192 # sysctl -w vm.dirty_background_ratio=0 With that setup defrag completely obliterates files even with default threshold value.