From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:43701 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753517Ab2HAGV5 (ORCPT ); Wed, 1 Aug 2012 02:21:57 -0400 Date: Tue, 31 Jul 2012 23:21:56 -0700 From: Marc MERLIN To: "Fajar A. Nugraha" Cc: "linux-btrfs@vger.kernel.org" Subject: Re: How can btrfs take 23sec to stat 23K files from an SSD? Message-ID: <20120801062156.GI12695@merlins.org> References: <20120722185848.GA10089@merlins.org> <201207222135.11159.Martin@lichtvoll.de> <20120722204428.GC3925@merlins.org> <20120722224145.GC12951@merlins.org> <20120723064202.GB6931@merlins.org> <20120727110835.GA6933@shiny> <20120801053042.GG12695@merlins.org> <20120727184238.GA6713@merlins.org> <20120801060135.GH12695@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Aug 01, 2012 at 01:08:46PM +0700, Fajar A. Nugraha wrote: > > It it were a random crappy SSD from a random vendor, I'd blame the SSD, but > > I have a hard time believing that samsung is selling SSDs that are slower > > than hard drives at random IO and 'seeks'. > > You'd be surprised on how badly some vendors can screw up :) At some point, it may come down to that indeed :-/ I'm still hopefully that Samsung didn't, but we'll see. > > First: btrfs is the slowest: > > > gandalfthegreat:/mnt/ssd/var/local# grep /mnt/ssd/var /proc/mounts > > /dev/mapper/ssd /mnt/ssd/var btrfs rw,noatime,compress=lzo,ssd,discard,space_cache 0 0 > > Just checking, did you explicitly activate "discard"? Cause on my Yes. Note that it should a noop when all you're doing is stating inodes and not writing (I'm using noatime). > setup (with corsair SSD) it made things MUCH slower. Also, try adding > "noatime" (just in case the slow down was because "du" cause many > access time updates) I have noatime in there already :) 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/