From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46705) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxZxc-0006S9-EC for qemu-devel@nongnu.org; Mon, 10 Apr 2017 10:06:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxZxX-0005uu-G7 for qemu-devel@nongnu.org; Mon, 10 Apr 2017 10:06:28 -0400 Received: from fanzine.igalia.com ([91.117.99.155]:35697) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cxZxX-0005fC-43 for qemu-devel@nongnu.org; Mon, 10 Apr 2017 10:06:23 -0400 From: Alberto Garcia In-Reply-To: <20170405151148.16363-5-stefanha@redhat.com> References: <20170405151148.16363-1-stefanha@redhat.com> <20170405151148.16363-5-stefanha@redhat.com> Date: Mon, 10 Apr 2017 16:05:42 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v4 4/9] qcow2: make refcount size calculation conservative List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Nir Soffer , Kevin Wolf , Maor Lipchuk , "Daniel P. Berrange" , Eric Blake , John Snow On Wed 05 Apr 2017 05:11:43 PM CEST, Stefan Hajnoczi wrote: > The refcount metadata size calculation is inaccurate and can produce > numbers that are too small. This is bad because we should calculate a > conservative number - one that is guaranteed to be large enough. > > This patch switches the approach to a fixed point calculation because > the existing equation is hard to solve when inaccuracies are taken care > of. > > Signed-off-by: Stefan Hajnoczi Reviewed-by: Alberto Garcia Berto