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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 7B93DC2BA15 for ; Sun, 5 Apr 2020 18:47:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CEAB20659 for ; Sun, 5 Apr 2020 18:47:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=libero.it header.i=@libero.it header.b="BChgpMFa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727390AbgDESrT (ORCPT ); Sun, 5 Apr 2020 14:47:19 -0400 Received: from smtp-35.italiaonline.it ([213.209.10.35]:56171 "EHLO libero.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726771AbgDESrT (ORCPT ); Sun, 5 Apr 2020 14:47:19 -0400 Received: from venice.bhome ([94.37.173.46]) by smtp-35.iol.local with ESMTPA id LAIdjBBKiMAUpLAIejSs1R; Sun, 05 Apr 2020 20:47:16 +0200 x-libjamoibt: 1601 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=libero.it; s=s2014; t=1586112436; bh=RDnNP7FIJuUKSoZ9DNeDVirXjDu5O7bsydqccwSDqKQ=; h=From; b=BChgpMFaKTTV/gcSg0xHMDvky3ykw0TAwAqjUyv0lkUIEdLA1rL51Qgy2UHaJxxBy 1TbvIkUfRLFY/XaWsFNTXK2rTBkCXYmH2r4UbV8rBRZUak1h1vxGfloNBRBT19kZd/ xLsGyTmHw6b609CiisQ4xUDxvke8ku3WNIDAZ2xuQx8yAeeQFk79Kz0W4CwhTHKK+E PyGIQX+z+jQ/bk5okaCwZxDbzMqVfCIqpV3kX5d7HQ+TlE5MK8T9AdmqvGaL5q0wr4 uyOv8NSCPdf21KRjWS9WAfMYFQrfN51v7Izt0ErjUEYLtTbEDls+pL+KHgay1TcZxi 1itSg+3UQB/ow== X-CNFS-Analysis: v=2.3 cv=B/fHL9lM c=1 sm=1 tr=0 a=TpQr5eyM7/bznjVQAbUtjA==:117 a=TpQr5eyM7/bznjVQAbUtjA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=IkcTkHD0fZMA:10 a=PBbJxcHo1tzoxWNbgcUA:9 a=QEXdDO2ut3YA:10 Reply-To: kreijack@inwind.it Subject: Re: [RFC][PATCH V3] btrfs: ssd_metadata: storing metadata on SSD To: Graham Cobb , linux-btrfs@vger.kernel.org References: <20200405082636.18016-1-kreijack@libero.it> <58e315a1-0307-9a26-8fb4-fd5220c1d5a6@cobb.uk.net> From: Goffredo Baroncelli Message-ID: <4f10882a-fa89-25e0-901c-aff8010d46cd@libero.it> Date: Sun, 5 Apr 2020 20:47:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <58e315a1-0307-9a26-8fb4-fd5220c1d5a6@cobb.uk.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfJPQHGQbvDXlKaGMyqrC7FR3iv3po4Ya+ct4YrtL4Qs9UY+f2PaLxkFeJa6bWsxhOL9lvYYjT3/WuSceagbmUGX/OMXGi5kDCO2Owv5cuT19tD0fP2va UAPI93WOyI+esVrH9Vvq6zdXdBYzgqe9inVn4p2vJ+FFTuk6bxwxElsbc5bFD54A1dxslLJX/DtzJv5kJ/YzfhsVIH4q6ewMlpQ= Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 4/5/20 12:57 PM, Graham Cobb wrote: > On 05/04/2020 09:26, Goffredo Baroncelli wrote: [...] >> >> >> Test description real (mmm:ss) Delta % >> -------------------- ------------- ------- >> btrfs hdd w/sync 142:38 +533% >> btrfs ssd+hdd w/sync 81:04 +260% >> ext4 hdd w/sync 52:39 +134% >> btrfs bcache w/sync 35:59 +60% >> btrfs ssd w/sync 22:31 reference >> ext4 ssd w/syn 12:19 -45% > > Interesting data but it seems to be missing the case of btrfs ssd+hdd > w/sync without your patch in order to tell what difference your patch > made. Or am I confused? > Currently BTRFS allocates the chunk on the basis of the free space. For my tests I have a smaller ssd (20GB) and a bigger hdd (230GB). This means that the latter has higher priority for the allocation, until the free space became equal. The rationale behind my patch is the following: - is quite simple (even tough in 3 iteration I put two errors :-) ) - BTRFS has already two kind of information to store: data and metadata. The former is (a lot ) bigger, than the latter. Having two kind of storage, one faster (and expensive) than the other, it is natural to put the metadata in the faster one, and the data in the slower one. BR G.Baroncelli -- gpg @keyserver.linux.it: Goffredo Baroncelli Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5