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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 4B3E5C282DD for ; Tue, 7 Jan 2020 19:26:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AACE20656 for ; Tue, 7 Jan 2020 19:26:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728454AbgAGT0w (ORCPT ); Tue, 7 Jan 2020 14:26:52 -0500 Received: from mail.itouring.de ([188.40.134.68]:39062 "EHLO mail.itouring.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728307AbgAGT0w (ORCPT ); Tue, 7 Jan 2020 14:26:52 -0500 Received: from tux.applied-asynchrony.com (p5B07E981.dip0.t-ipconnect.de [91.7.233.129]) by mail.itouring.de (Postfix) with ESMTPSA id 034F84163429; Tue, 7 Jan 2020 20:26:50 +0100 (CET) Received: from [192.168.100.223] (ragnarok.applied-asynchrony.com [192.168.100.223]) by tux.applied-asynchrony.com (Postfix) with ESMTP id 5ED1FF01600; Tue, 7 Jan 2020 20:26:49 +0100 (CET) Subject: Re: write amplification, was: very slow "btrfs dev delete" 3x6Tb, 7Tb of data To: Chris Murphy , Zygo Blaxell , Btrfs BTRFS References: <6058c4c4-fcb3-c7cd-6517-10b5908b34da@georgianit.com> <602a4895-f2f7-f024-c312-d880f12e1360@dubiel.pl> <2c135c87-d01b-53f1-9f76-a5653918a4e7@dubiel.pl> <20191228202344.GE13306@hungrycats.org> <5e6e2ff8-89be-45db-49d3-802de42663ed@dubiel.pl> <20200104053843.GK13306@hungrycats.org> From: =?UTF-8?Q?Holger_Hoffst=c3=a4tte?= Organization: Applied Asynchrony, Inc. Message-ID: Date: Tue, 7 Jan 2020 20:26:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed 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 1/7/20 7:44 PM, Chris Murphy wrote: > Egads! Soo... total tangent. I'll change the subject. Time for science! "Analyzing IO Amplification in Linux File Systems" https://arxiv.org/abs/1707.08514 Ironically Btrfs does better in a related paper: "Filesystem Aging: It’s more Usage than Fullness" https://www.usenix.org/conference/hotstorage19/presentation/conway enjoy, Holger