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 X-Spam-Level: X-Spam-Status: No, score=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BD89C433E0 for ; Sat, 16 Jan 2021 07:43:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56AF823370 for ; Sat, 16 Jan 2021 07:43:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726680AbhAPHkg (ORCPT ); Sat, 16 Jan 2021 02:40:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726451AbhAPHkf (ORCPT ); Sat, 16 Jan 2021 02:40:35 -0500 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E5DBC061757 for ; Fri, 15 Jan 2021 23:39:55 -0800 (PST) Received: by mail-lf1-x12a.google.com with SMTP id a12so16632410lfl.6 for ; Fri, 15 Jan 2021 23:39:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=XoiM4ecB1QgvcdLUV/9jgk42vnfgyH+qg88CbsAfZIE=; b=imwsieIIQAQ+PJ/ilxOEQa03RmFPGVX5W5/JnnNRxM5Pcv70YGhTLGhKyua56zT8Pn +WmLgk1yjy2NRNfT3jwJ6y/mzRYc379OkNhq+HarGCfd9LreL8H3ocpErH0b/HJOz+eQ UfKQ2YszvXbjbSWqnW97bHWgnHhUOloULPi9nyyopAa/jajUV+6Y67VLWvv1haCxWvRm xI6+1ur5NsVH3igyk3u+0pGYkNcu3vgmcPVVaviWI6U7WhhhaYwN4uIO4sg3tn/7B0hw X/SCjDvZ7TrSdjFxulRfHZPXwmXPDY4YgKFx9U7Po5r9+X4qXnzYlCP64Y1loIJyDOR9 KsFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:autocrypt:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=XoiM4ecB1QgvcdLUV/9jgk42vnfgyH+qg88CbsAfZIE=; b=iMTYYd4VltIfbO1MD+bm+0CE8UshJy6sS8Gxd6reE+dYVBgDNEIeG3KXLvgA6oyUMl DHXoLUEkts7SAvM2ECJEIT292jxDbEAnr9gWoAoNVTyia3LMgHJL0k8bU7zHbkQpo7Ts DRtPCFWYEZ+9bI/qaRlrwyjXkxsH4xPxSasV4Inym4p83xOE8okWlil0hGYZzsyul+7O jcNb7vJO+fJMb56PeoQqhm4oEWN5vqS2hXXzCQOBGnoyMnZWHYebPREjvUyuKU6Py+vG nhagz5Vjf9KJCRVl6YnRE00P3S5jpVs2gCjNz0Vyb37q12Xbzcg2UB6i2WGZCP32YuKk 1eTg== X-Gm-Message-State: AOAM5302bgNKvkUANZTieS0dFL4YT/uysP8HCoRvx7NdTkdSiR8q2QOm ax39T/L2Ec3RRV0XQ98+y4w+iVPN0ZRFgg== X-Google-Smtp-Source: ABdhPJz8zwYdIW5XYhcFXlDYAhPDjycZiifLRJC/7GGZB6fexn4ApTpGojsE0GwlOdKlFgcW0GCqoA== X-Received: by 2002:a05:6512:2103:: with SMTP id q3mr6997185lfr.404.1610782793355; Fri, 15 Jan 2021 23:39:53 -0800 (PST) Received: from ?IPv6:2a00:1370:812d:ecb3:590f:aaab:50ba:573b? ([2a00:1370:812d:ecb3:590f:aaab:50ba:573b]) by smtp.gmail.com with ESMTPSA id 187sm1181568lfo.16.2021.01.15.23.39.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Jan 2021 23:39:52 -0800 (PST) Subject: Re: Why do we need these mount options? To: Zygo Blaxell , dsterba@suse.cz, waxhead , linux-btrfs@vger.kernel.org References: <208dba68-b47e-101d-c893-8173df8fbbbf@dirtcellar.net> <20210114163729.GY6430@twin.jikos.cz> <20210115035448.GD31381@hungrycats.org> From: Andrei Borzenkov Autocrypt: addr=arvidjaar@gmail.com; prefer-encrypt=mutual; keydata= mQGiBDxiRwwRBAC3CN9wdwpVEqUGmSoqF8tWVIT4P/bLCSZLkinSZ2drsblKpdG7x+guxwts +LgI8qjf/q5Lah1TwOqzDvjHYJ1wbBauxZ03nDzSLUhD4Ms1IsqlIwyTLumQs4vcQdvLxjFs G70aDglgUSBogtaIEsiYZXl4X0j3L9fVstuz4/wXtwCg1cN/yv/eBC0tkcM1nsJXQrC5Ay8D /1aA5qPticLBpmEBxqkf0EMHuzyrFlqVw1tUjZ+Ep2LMlem8malPvfdZKEZ71W1a/XbRn8FE SOp0tUa5GwdoDXgEp1CJUn+WLurR0KPDf01E4j/PHHAoABgrqcOTcIVoNpv2gNiBySVsNGzF XTeY/Yd6vQclkqjBYONGN3r9R8bWA/0Y1j4XK61qjowRk3Iy8sBggM3PmmNRUJYgroerpcAr 2byz6wTsb3U7OzUZ1Llgisk5Qum0RN77m3I37FXlIhCmSEY7KZVzGNW3blugLHcfw/HuCB7R 1w5qiLWKK6eCQHL+BZwiU8hX3dtTq9d7WhRW5nsVPEaPqudQfMSi/Ux1kbQmQW5kcmV5IEJv cnplbmtvdiA8YXJ2aWRqYWFyQGdtYWlsLmNvbT6IYAQTEQIAIAUCSXs6NQIbAwYLCQgHAwIE FQIIAwQWAgMBAh4BAheAAAoJEEeizLraXfeMLOYAnj4ovpka+mXNzImeYCd5LqW5to8FAJ4v P4IW+Ic7eYXxCLM7/zm9YMUVbrQmQW5kcmVpIEJvcnplbmtvdiA8YXJ2aWRqYWFyQGdtYWls LmNvbT6IZQQTEQIAJQIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AFAliWAiQCGQEACgkQ R6LMutpd94wFGwCeNuQnMDxve/Fo3EvYIkAOn+zE21cAnRCQTXd1hTgcRHfpArEd/Rcb5+Sc uQENBDxiRyQQBACQtME33UHfFOCApLki4kLFrIw15A5asua10jm5It+hxzI9jDR9/bNEKDTK SciHnM7aRUggLwTt+6CXkMy8an+tVqGL/MvDc4/RKKlZxj39xP7wVXdt8y1ciY4ZqqZf3tmm SN9DlLcZJIOT82DaJZuvr7UJ7rLzBFbAUh4yRKaNnwADBwQAjNvMr/KBcGsV/UvxZSm/mdpv UPtcw9qmbxCrqFQoB6TmoZ7F6wp/rL3TkQ5UElPRgsG12+Dk9GgRhnnxTHCFgN1qTiZNX4YI FpNrd0au3W/Xko79L0c4/49ten5OrFI/psx53fhYvLYfkJnc62h8hiNeM6kqYa/x0BEddu92 ZG6IRgQYEQIABgUCPGJHJAAKCRBHosy62l33jMhdAJ48P7WDvKLQQ5MKnn2D/TI337uA/gCg n5mnvm4SBctbhaSBgckRmgSxfwQ= Message-ID: <94a65b16-3a23-6862-9de6-169620302308@gmail.com> Date: Sat, 16 Jan 2021 10:39:51 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210115035448.GD31381@hungrycats.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 15.01.2021 06:54, Zygo Blaxell пишет: > > On the other hand, I'm in favor of deprecating the whole discard option > and going with fstrim instead. discard in its current form tends to > increase write wear rather than decrease it, especially on metadata-heavy > workloads. discard is roughly equivalent to running fstrim thousands > of times a day, which is clearly bad for many (most? all?) SSDs. > My (probably naive) understanding so far was that trim on SSD marks areas as "unused" which means SSD need to copy less residual data from erase block when reusing it. Assuming TRIM unit is (significantly) smaller than erase block. I would appreciate if you elaborate how trim results in more write on SSD? Or do you mean more writes from btrfs while performing discard?