From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38615) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UopM6-0004ys-MF for qemu-devel@nongnu.org; Tue, 18 Jun 2013 02:25:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UopM5-0000TL-2C for qemu-devel@nongnu.org; Tue, 18 Jun 2013 02:25:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10220) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UopM4-0000T5-PB for qemu-devel@nongnu.org; Tue, 18 Jun 2013 02:25:24 -0400 Date: Tue, 18 Jun 2013 08:25:19 +0200 From: Kevin Wolf Message-ID: <20130618062519.GA3640@dhcp-200-207.str.redhat.com> References: <1371124063-12971-1-git-send-email-kwolf@redhat.com> <51BFCE0E.5050408@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51BFCE0E.5050408@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH 0/5] qcow2: Discard freed clusters List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wenchao Xia Cc: qemu-devel@nongnu.org, stefanha@redhat.com Am 18.06.2013 um 05:03 hat Wenchao Xia geschrieben: > Hi, Kevin > In normal case, qcow2 is based on raw-posix file which don't support > discard operation It does, see raw_aio_discard(). > , so this serial doesn't change much in this case, > still real space is not freed in snapshot delete, and it completes > fast. Instead, tt affects the case that some protocol below support > discard, so delete will be more clean but slower in that case. Is this > true? Maybe add this in commit message? Yes, it becomes a little bit slower, but not much in my tests. Kevin