From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.dpl.mendix.net ([83.96.177.10]:35208 "EHLO smtp.dpl.mendix.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932724AbdKBPKh (ORCPT ); Thu, 2 Nov 2017 11:10:37 -0400 Subject: Re: Multiple btrfs-cleaner threads per volume To: Martin Raiber , "linux-btrfs@vger.kernel.org" References: <0102015f7d418aa6-af3c2ae7-27b0-47d0-a4bb-173f55304bb9-000000@eu-west-1.amazonses.com> From: Hans van Kranenburg Message-ID: <75dfd17b-3f3a-dc22-e069-d68faa33eb8e@mendix.com> Date: Thu, 2 Nov 2017 16:10:35 +0100 MIME-Version: 1.0 In-Reply-To: <0102015f7d418aa6-af3c2ae7-27b0-47d0-a4bb-173f55304bb9-000000@eu-west-1.amazonses.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi Martin, On 11/02/2017 04:02 PM, Martin Raiber wrote: > > snapshot cleanup is a little slow in my case (50TB volume). Would it > help to have multiple btrfs-cleaner threads? The block layer underneath > would have higher throughput with more simultaneous read/write requests. Just curious: * How many subvolumes/snapshots are you removing, and what's the complexity level (like, how many other subvolumes/snapshots reference the same data extents?) * Do you see a lot of cpu usage, or mainly a lot of disk I/O? If it's disk IO, is it mainly random read IO, or is it a lot of write traffic? * What mount options are you running with (from /proc/mounts)? -- Hans van Kranenburg