From: Ted Ts'o Subject: Re: Ext4: batched discard support - simplified version Date: Fri, 23 Jul 2010 11:19:25 -0400 Message-ID: <20100723151925.GI13090@thunk.org> References: <1278489212-12110-1-git-send-email-lczerner@redhat.com> <20100723143604.GF13090@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Lukas Czerner , eshishki@redhat.com, rwheeler@redhat.com, linux-ext4@vger.kernel.org, sandeen@redhat.com To: Jeff Moyer Return-path: Received: from thunk.org ([69.25.196.29]:42085 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753208Ab0GWPT1 (ORCPT ); Fri, 23 Jul 2010 11:19:27 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Jul 23, 2010 at 11:13:52AM -0400, Jeff Moyer wrote: > > I don't think so. In all of the configurations tested, I'm pretty sure > we saw a performance hit from doing the TRIMs right away. The queue > flush really hurts. Of course, I have no idea what you had in mind for > the amount of time in between batched discards. Sure, but not all the world is SATA-attached SSD's. I'm thinking in particular of PCIe-attached SSD's, where the TRIM command might be very fast indeed... I believe Ric Wheeler tells me you have TMS RamSan SSD's in house that you are testing? And of course those aren't the only PCIe-attached flash devices out there.... - Ted