From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:52448 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271Ab3C0QxK (ORCPT ); Wed, 27 Mar 2013 12:53:10 -0400 Received: from merlin by mail1.merlins.org with local (Exim 4.80 #2) id 1UKtb3-00078I-UW for ; Wed, 27 Mar 2013 09:53:09 -0700 Date: Wed, 27 Mar 2013 09:53:09 -0700 From: Marc MERLIN To: linux-btrfs@vger.kernel.org Subject: zlib vs lzo uncompress speed, ssd vs nossd Message-ID: <20130327165309.GA23559@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-btrfs-owner@vger.kernel.org List-ID: I just setup a new SSD with my laptop root filesystem, and at the time I though, "eh, I'll just use zlib compression during the first copy, and then switch to lzo afterwards to maintain write speed when I'm using the laptop after the copy and reboot". Now, I rebooted with the new ssd and zlib compressed rootfs, and it seemed to boot slower than it did before with the same root files on btrfs lzo. My mount options are back to lzo: /dev/mapper/cryptroot / btrfs rw,noatime,compress=lzo,nossd,discard,space_cache 0 0 Is my feeling of slower boot wrong, or is zlib also noticeably slower than lzo to read and decompress? And separately, back a while ago, I read in multiple places that 'nossd' actually worked better than 'ssd'. This was over a year ago now. What's the current consensus on ssd and nosdd? Am I correct that it mostly affects how data is layed out at write time by btrfs? Should I go back to trying ssd instead of nossd? 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/