From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mondschein.lichtvoll.de ([194.150.191.11]:60582 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756967Ab3BAUs2 convert rfc822-to-8bit (ORCPT ); Fri, 1 Feb 2013 15:48:28 -0500 From: Martin Steigerwald To: linux-btrfs@vger.kernel.org Subject: Re: /home on BTRFS on SSD, now highly fragmenting virtuoso database - use autodefrag? Date: Fri, 1 Feb 2013 21:48:20 +0100 Cc: Hugo Mills References: <201301311444.12314.Martin@lichtvoll.de> <20130131215810.GO16285@carfax.org.uk> (sfid-20130201_000531_601694_2DCE9020) In-Reply-To: <20130131215810.GO16285@carfax.org.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Message-Id: <201302012148.20899.Martin@lichtvoll.de> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Am Donnerstag, 31. Januar 2013 schrieb Hugo Mills: > On Thu, Jan 31, 2013 at 02:44:12PM +0100, Martin Steigerwald wrote: > > Hi! > > > > Today I converted my /home from Ext4 to BTRFS by reformatting and copying > > all over again. > > > > I created the filesystem with -l 16384 -n 16384 -d single -m single on an > > logical volume Intel SSD 320 and mount with compress=lzo,spacecache. Current state: > > The way that compression is implemented in btrfs, compressed files > always look fragmented, even if they're not. Basically, each > compression block shows up as a single fragment. If the blocks are > next to each other, the file's not actually fragmented, but still > looks like it to fiemap. Ah, thanks. Thats interesting to know. > [snip] > > Except for a highly fragmenting file: > > > > martin@merkaba:~/.kde/share/apps/nepomuk/repository/main/data/virtuosobackend> ls -lh > > insgesamt 1,2G > > -rw------- 1 martin martin 1,3G Jan 31 14:07 soprano-virtuoso.db > > -rw-r--r-- 1 martin martin 14 Jan 31 14:06 soprano-virtuoso.lck > > -rw------- 1 martin martin 0 Jan 27 17:52 soprano-virtuoso.lock > > -rw-r--r-- 1 martin martin 13K Jan 31 10:22 soprano-virtuoso.log > > -rw-r--r-- 1 martin martin 0 Jan 27 17:52 soprano-virtuoso.pxa > > -rw-r--r-- 1 martin martin 8,0M Jan 31 14:07 soprano-virtuoso-temp.db > > -rw-r--r-- 1 martin martin 14K Jan 31 14:07 soprano-virtuoso.trx > > > > > > martin@merkaba:~/.kde/share/apps/nepomuk/repository/main/data/virtuosobackend> sudo filefrag soprano-virtuoso.db > > [sudo] password for martin: > > soprano-virtuoso.db: 481 extents found > > […] > > > Now I do not perceive any bottle neck so far and this is an SSD. > > > > What would be your recommendation: Add autodefrag to mount options or not? > > For an SSD, probably not worth it. Thanks. I then will use what I advice attendees to my Linux Performance Analysis & Performance trainings and what XFS guys are also advicing: Use the defaults (unless you know otherwise). Especially since I think the Intel SSD 320 is one of the better ones and desktop search is really snappy up to know. Thanks, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7