From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:47912 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752300Ab2GWGmJ (ORCPT ); Mon, 23 Jul 2012 02:42:09 -0400 Received: from [173.11.111.150] (port=34153 helo=gandalfthegreat.merlins.org) by mail1.merlins.org with esmtpa (Exim 4.77 #2) id 1StCLI-00083u-Q7 by authid with srv_auth_plain for ; Sun, 22 Jul 2012 23:42:08 -0700 Received: from merlin by gandalfthegreat.merlins.org with local (Exim 4.77) (envelope-from ) id 1StCLD-0001rG-NG for linux-btrfs@vger.kernel.org; Sun, 22 Jul 2012 23:42:03 -0700 Date: Sun, 22 Jul 2012 23:42:03 -0700 From: Marc MERLIN To: linux-btrfs@vger.kernel.org Subject: How can btrfs take 23sec to stat 23K files from an SSD? Message-ID: <20120723064202.GB6931@merlins.org> References: <20120202124241.GW16796@shiny> <20120718220446.GB3888@merlins.org> <20120722185848.GA10089@merlins.org> <201207222135.11159.Martin@lichtvoll.de> <20120202124241.GW16796@shiny> <20120718220446.GB3888@merlins.org> <20120722185848.GA10089@merlins.org> <201207222135.11159.Martin@lichtvoll.de> <20120722204428.GC3925@merlins.org> <20120722224145.GC12951@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20120722224145.GC12951@merlins.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: I just realized that the older thread got a bit confusing, so I'll keep problems separate and make things simpler :) On an _unencrypted_ partition on the SSD, running du -sh on a directory with 15K files, takes 23 seconds on unencrypted SSD and 4 secs on encrypted spinning drive, both with a similar btrfs filesystem, and the same kernel (3.4.4). Unencrypted btrfs on SSD: gandalfthegreat:~# mount -o compress=lzo,discard,nossd,space_cache,noatime /dev/sda2 /mnt/mnt2 gandalfthegreat:/mnt/mnt2# echo 3 > /proc/sys/vm/drop_caches; time du -sh src 514M src real 0m22.667s Encrypted btrfs on spinning drive of the same src directory: gandalfthegreat:/var/local# echo 3 > /proc/sys/vm/drop_caches; time du -sh src 514M src real 0m3.881s I've run this many times and get the same numbers. I've tried deadline and noop on /dev/sda (the SSD) and du is just as slow. I also tried with: - space_cache and nospace_cache - ssd and nossd - noatime didn't seem to help even though I was hopeful on this one. In all cases, I get: gandalfthegreat:/mnt/mnt2# echo 3 > /proc/sys/vm/drop_caches; time du -sh src 514M src real 0m22.537s I'm having the same slow speed on 2 btrfs filesystems on the same SSD. One is encrypted, the other one isnt: Label: 'btrfs_pool1' uuid: d570c40a-4a0b-4d03-b1c9-cff319fc224d Total devices 1 FS bytes used 144.74GB devid 1 size 441.70GB used 195.04GB path /dev/dm-0 Label: 'boot' uuid: 84199644-3542-430a-8f18-a5aa58959662 Total devices 1 FS bytes used 2.33GB devid 1 size 25.00GB used 5.04GB path /dev/sda2 If instead of stating a bunch of files, I try reading a big file, I do get speeds that are quite fast (253MB/s and 423MB/s). 22 seconds for 15K files on an SSD is super slow and being 5 times slower than a spinning disk with the same data. What's going on? Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/