From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f179.google.com ([209.85.220.179]:34013 "EHLO mail-qk0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932430AbcCPLyr (ORCPT ); Wed, 16 Mar 2016 07:54:47 -0400 Received: by mail-qk0-f179.google.com with SMTP id x1so19454225qkc.1 for ; Wed, 16 Mar 2016 04:54:46 -0700 (PDT) Subject: Re: Major HDD performance degradation on btrfs receive To: Chris Murphy , Nazar Mokrynskyi , Btrfs BTRFS References: <72cb240a-fdb2-c38b-adb1-2b72847ab29a@mokrynskyi.com> <5240211f-27b7-2c87-41e7-c10953374921@mokrynskyi.com> <1557fe0b-bbcc-c125-5220-46a56e936590@mokrynskyi.com> From: "Austin S. Hemmelgarn" Message-ID: <56E94934.4030306@gmail.com> Date: Wed, 16 Mar 2016 07:53:24 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2016-03-16 02:51, Chris Murphy wrote: > On Tue, Mar 15, 2016 at 10:23 PM, Nazar Mokrynskyi wrote: >> Sounds like a really good idea! >> >> I'll try to implement in in my backup tool, but it might take some time to >> see real benefit from it (or no benefit:)). > > There is a catch. I'm not sure how much testing deleting 100 > subvolumes at once gets. It should work. I haven't looked in xfstests > to see how much of this is being tested. So it's possible you're > testing it. So be ready. I've actually tested bulk removal of large numbers of snapshots multiple times before (it's actually one of the things that isn't in xfstests that I check when testing patches, I usually test power of two groups from 16 up to 256 at a time). It works, but it may tie up most of the disk bandwidth for a while depending on what type of storage you're using.