From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755160AbZHPPpU (ORCPT ); Sun, 16 Aug 2009 11:45:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752679AbZHPPpR (ORCPT ); Sun, 16 Aug 2009 11:45:17 -0400 Received: from THUNK.ORG ([69.25.196.29]:53360 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905AbZHPPpP (ORCPT ); Sun, 16 Aug 2009 11:45:15 -0400 Date: Sun, 16 Aug 2009 11:44:30 -0400 From: Theodore Tso To: Arjan van de Ven Cc: Alan Cox , James Bottomley , Mark Lord , Chris Worley , Matthew Wilcox , Bryan Donlan , david@lang.hm, Greg Freemyer , Markus Trippelsdorf , Matthew Wilcox , Hugh Dickins , Nitin Gupta , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, Linux RAID Subject: Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed) Message-ID: <20090816154430.GE17958@mit.edu> Mail-Followup-To: Theodore Tso , Arjan van de Ven , Alan Cox , James Bottomley , Mark Lord , Chris Worley , Matthew Wilcox , Bryan Donlan , david@lang.hm, Greg Freemyer , Markus Trippelsdorf , Matthew Wilcox , Hugh Dickins , Nitin Gupta , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, Linux RAID References: <3e8340490908131354q167840fcv124ec56c92bbb830@mail.gmail.com> <4A85E0DC.9040101@rtr.ca> <20090814234539.GE27148@parisc-linux.org> <1250341176.4159.2.camel@mulgrave.site> <4A86B69C.7090001@rtr.ca> <1250344518.4159.4.camel@mulgrave.site> <20090816150530.2bae6d1f@lxorguk.ukuu.org.uk> <20090816083434.2ce69859@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090816083434.2ce69859@infradead.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@mit.edu X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 16, 2009 at 08:34:34AM -0700, Arjan van de Ven wrote: > trim is mostly for ssd's though, and those tend to not have the "goes > for a hike" behavior as much...... Mark Lord has claimed that the currently shipping SSD's take "hundreds of milliseconds" for a TRIM, command. Compared to the usual latency of an SSD, that could very well be considered "takes a coffee break" behaviour; maybe not "goes for a hike", but enough that you wouldn't want to be doing one all the time. The story that I've heard which worries me is that those of us which were silly enough to spend $400 and $800 dollars on the first generation X25-M drives may never get TRIM support, and that TRIM support might only be offered on the second generation X25-M drives. I certainly _hope_ that is not true, but in any case, I don't have any TRIM capable drives at the moment, so it's not something which I'm set up to test.... - Ted