From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59685) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SBSvT-0008FU-NX for qemu-devel@nongnu.org; Sat, 24 Mar 2012 11:30:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SBSvS-0006cp-17 for qemu-devel@nongnu.org; Sat, 24 Mar 2012 11:30:43 -0400 Received: from verein.lst.de ([213.95.11.211]:52360 helo=newverein.lst.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SBSvR-0006ce-QW for qemu-devel@nongnu.org; Sat, 24 Mar 2012 11:30:41 -0400 Date: Sat, 24 Mar 2012 16:30:40 +0100 From: Christoph Hellwig Message-ID: <20120324153040.GC13014@lst.de> References: <1331226917-6658-1-git-send-email-pbonzini@redhat.com> <1331226917-6658-7-git-send-email-pbonzini@redhat.com> <4F5A31B2.3050701@redhat.com> <4F5A46A1.4000508@redhat.com> <1331402560.8577.46.camel@watermelon.coderich.net> <4F5DEBCE.3040409@redhat.com> <1331665990.24052.42.camel@watermelon.coderich.net> <4F604B98.9090606@redhat.com> <4F60889F.6030401@redhat.com> <4F608B9A.8040406@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F608B9A.8040406@redhat.com> Subject: Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Kevin Wolf , Richard Laager , qemu-devel@nongnu.org On Wed, Mar 14, 2012 at 01:14:18PM +0100, Paolo Bonzini wrote: > > Note that the discard granularity is only a hint, so it's really more a > maximum suggested value than a granularity. Outside of a cluster > boundary the format would still have to write zeros manually. > > Also, Linux for example will only round the number of sectors down to > the granularity, not the start sector. Which really is more of a bug than a feature. The current discard implementation in Linux is still very poor.