From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:57066 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750704AbaCOEVR (ORCPT ); Sat, 15 Mar 2014 00:21:17 -0400 Date: Fri, 14 Mar 2014 21:21:16 -0700 From: Marc MERLIN To: Holger =?iso-8859-1?Q?Hoffst=E4tte?= Cc: linux-btrfs@vger.kernel.org Subject: Re: discard synchronous on most SSDs? Message-ID: <20140315042116.GK6143@merlins.org> References: <20140314051750.GY6143@merlins.org> <531C1CC4.701@gmail.com> <20140314051750.GY6143@merlins.org> <5289248.oqpgSKG6td@quad> <20140314192605.GD6143@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Mar 14, 2014 at 08:46:09PM +0000, Holger Hoffstätte wrote: > On Fri, 14 Mar 2014 15:57:41 -0400, Martin K. Petersen wrote: > > > So right now I'm afraid we don't have a good way for a user to determine > > whether a device supports queued trims or not. > > Mount with discard, unpack kernel tree, sync, rm -rf tree. > If it takes several seconds, you have sync discard, no? Mmmh, interesting point. legolas:/usr/src# time rm -rf linux-3.14-rc5 real 0m1.584s user 0m0.008s sys 0m1.524s I remounted my FS with remount,nodiscard, and the time was the same. > This changed somewhere around kernel 3.8.x; before that it used to be > acceptably fast. Since then I only do batch trims, daily (server) or > weekly (laptop). I'm never really timed this before. Is it supposed to be faster than 1.5s on a fast SSD? 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/