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=-5.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 9A742C433E2 for ; Wed, 2 Sep 2020 10:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DE8320658 for ; Wed, 2 Sep 2020 10:09:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726489AbgIBKJc (ORCPT ); Wed, 2 Sep 2020 06:09:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:53690 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbgIBKJb (ORCPT ); Wed, 2 Sep 2020 06:09:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 55629B080; Wed, 2 Sep 2020 10:09:31 +0000 (UTC) Subject: Re: new database files not compressed To: A L , Hamish Moffatt , linux-btrfs@vger.kernel.org References: <6992fae3-ce87-8ae1-8dfe-1cb65578a16a@moffatt.email> <20200831034731.GX5890@hungrycats.org> <20200831161505.369be693@natsu> <41107373-cc61-ea3f-7ae9-c9eef0ee47f9@suse.com> <2d060b13-7a1a-7cc5-927f-2c6a067f9c03@moffatt.email> <0bf29a8c-23b2-26f4-2efd-2e82f38c437d@suse.com> <4c3d4141-4452-bb79-b18e-f32c8e35cb13@moffatt.email> <03ec55ee-5cf3-54fa-1a81-abc93006ca7b@suse.com> From: Nikolay Borisov Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= xsFNBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABzSJOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuZGU+wsF4BBMBAgAiBQJYijkSAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRBxvoJG5T8oV/B6D/9a8EcRPdHg8uLEPywuJR8URwXzkofT5bZE IfGF0Z+Lt2ADe+nLOXrwKsamhweUFAvwEUxxnndovRLPOpWerTOAl47lxad08080jXnGfYFS Dc+ew7C3SFI4tFFHln8Y22Q9075saZ2yQS1ywJy+TFPADIprAZXnPbbbNbGtJLoq0LTiESnD w/SUC6sfikYwGRS94Dc9qO4nWyEvBK3Ql8NkoY0Sjky3B0vL572Gq0ytILDDGYuZVo4alUs8 LeXS5ukoZIw1QYXVstDJQnYjFxYgoQ5uGVi4t7FsFM/6ykYDzbIPNOx49Rbh9W4uKsLVhTzG BDTzdvX4ARl9La2kCQIjjWRg+XGuBM5rxT/NaTS78PXjhqWNYlGc5OhO0l8e5DIS2tXwYMDY LuHYNkkpMFksBslldvNttSNei7xr5VwjVqW4vASk2Aak5AleXZS+xIq2FADPS/XSgIaepyTV tkfnyreep1pk09cjfXY4A7qpEFwazCRZg9LLvYVc2M2eFQHDMtXsH59nOMstXx2OtNMcx5p8 0a5FHXE/HoXz3p9bD0uIUq6p04VYOHsMasHqHPbsMAq9V2OCytJQPWwe46bBjYZCOwG0+x58 fBFreP/NiJNeTQPOa6FoxLOLXMuVtpbcXIqKQDoEte9aMpoj9L24f60G4q+pL/54ql2VRscK d87BTQRYigc+ARAAyJSq9EFk28++SLfg791xOh28tLI6Yr8wwEOvM3wKeTfTZd+caVb9gBBy wxYhIopKlK1zq2YP7ZjTP1aPJGoWvcQZ8fVFdK/1nW+Z8/NTjaOx1mfrrtTGtFxVBdSCgqBB jHTnlDYV1R5plJqK+ggEP1a0mr/rpQ9dFGvgf/5jkVpRnH6BY0aYFPprRL8ZCcdv2DeeicOO YMobD5g7g/poQzHLLeT0+y1qiLIFefNABLN06Lf0GBZC5l8hCM3Rpb4ObyQ4B9PmL/KTn2FV Xq/c0scGMdXD2QeWLePC+yLMhf1fZby1vVJ59pXGq+o7XXfYA7xX0JsTUNxVPx/MgK8aLjYW hX+TRA4bCr4uYt/S3ThDRywSX6Hr1lyp4FJBwgyb8iv42it8KvoeOsHqVbuCIGRCXqGGiaeX Wa0M/oxN1vJjMSIEVzBAPi16tztL/wQtFHJtZAdCnuzFAz8ue6GzvsyBj97pzkBVacwp3/Mw qbiu7sDz7yB0d7J2tFBJYNpVt/Lce6nQhrvon0VqiWeMHxgtQ4k92Eja9u80JDaKnHDdjdwq FUikZirB28UiLPQV6PvCckgIiukmz/5ctAfKpyYRGfez+JbAGl6iCvHYt/wAZ7Oqe/3Cirs5 KhaXBcMmJR1qo8QH8eYZ+qhFE3bSPH446+5oEw8A9v5oonKV7zMAEQEAAcLBXwQYAQIACQUC WIoHPgIbDAAKCRBxvoJG5T8oV1pyD/4zdXdOL0lhkSIjJWGqz7Idvo0wjVHSSQCbOwZDWNTN JBTP0BUxHpPu/Z8gRNNP9/k6i63T4eL1xjy4umTwJaej1X15H8Hsh+zakADyWHadbjcUXCkg OJK4NsfqhMuaIYIHbToi9K5pAKnV953xTrK6oYVyd/Rmkmb+wgsbYQJ0Ur1Ficwhp6qU1CaJ mJwFjaWaVgUERoxcejL4ruds66LM9Z1Qqgoer62ZneID6ovmzpCWbi2sfbz98+kW46aA/w8r 7sulgs1KXWhBSv5aWqKU8C4twKjlV2XsztUUsyrjHFj91j31pnHRklBgXHTD/pSRsN0UvM26 lPs0g3ryVlG5wiZ9+JbI3sKMfbdfdOeLxtL25ujs443rw1s/PVghphoeadVAKMPINeRCgoJH zZV/2Z/myWPRWWl/79amy/9MfxffZqO9rfugRBORY0ywPHLDdo9Kmzoxoxp9w3uTrTLZaT9M KIuxEcV8wcVjr+Wr9zRl06waOCkgrQbTPp631hToxo+4rA1jiQF2M80HAet65ytBVR2pFGZF zGYYLqiG+mpUZ+FPjxk9kpkRYz61mTLSY7tuFljExfJWMGfgSg1OxfLV631jV1TcdUnx+h3l Sqs2vMhAVt14zT8mpIuu2VNxcontxgVr1kzYA/tQg32fVRbGr449j1gw57BV9i0vww== Message-ID: <23ddfe07-9ad0-5651-a77d-de7a9e35818a@suse.com> Date: Wed, 2 Sep 2020 13:09:29 +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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2.09.20 г. 12:57 ч., A L wrote: > > > ---- From: Nikolay Borisov -- Sent: 2020-09-02 - 07:57 ---- >>> >>> I've been able to reproduce this with a trivial test program which >>> mimics the I/O behaviour of Firebird. >>> >>> It is calling fallocate() to set up a bunch of blocks and then writing >>> them with pwrite(). It seems to be the fallocate() step which is >>> preventing compression. >>> >>> Here is my trivial test program which just writes zeroes to a file. The >>> output file does not get compressed by btrfs. >> >> Ag yes, this makes sense, because fallocate creates PREALLOC extents >> which are NOCOW (since they are essentially empty so it makes no sense >> to CoW them) hence they go through a different path which doesn't >> perform compression. >> > > Hi, > > This is interesting. I think that a lot of applications use fallocate in their normal operations. This is probably why we see weird compsize results every now and then. > > A file that is nocow will also not have checksums. Is this true for these fallocated files (that has data written to them) too? No, fallocated files will have checksums. It's just that compression is not integrated into it. BTRFS is an open source project so patches are welcomed. > > I would really like to see that Btrfs was corrected so that writes to an fallocated area will be compressed (if one is using compression that is). > > Thanks. >