From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 1/3] blkdev: Submit discard bio in batches in blkdev_issue_discard() Date: Mon, 9 May 2011 10:30:27 -0400 Message-ID: <20110509143027.GA29635@infradead.org> References: <1304345841-20063-1-git-send-email-lczerner@redhat.com> <4DBEDA78.7020502@fusionio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jens Axboe , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Dmitry Monakhov , Jeff Moyer To: Lukas Czerner Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:46614 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753404Ab1EIOaa (ORCPT ); Mon, 9 May 2011 10:30:30 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, May 05, 2011 at 05:20:40PM +0200, Lukas Czerner wrote: > > Good results. It'd be more efficient to add the vectored discard support > > and use it for this too though, and it would get rid of the need to wait > > on the batches since there'd be just one discard bio for the ranges. > > > > Since we do not have vectored discard yet, can this change go in as it > is ? Also, Christoph thinks that it would not help anyway since the we do > batch the discard requests only when it exceeds the max range. I think this patch is orthogonal to vectored discard. The batching is important for large ranges which generally come from BLKDISCARD or FITRIM, while vectored discard is mostly interesting for lots of small discards at transaction commit time.