From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43905) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dv55t-0006Fb-IA for qemu-devel@nongnu.org; Thu, 21 Sep 2017 13:16:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dv55p-00031C-Je for qemu-devel@nongnu.org; Thu, 21 Sep 2017 13:16:57 -0400 References: <1501597152-25342-1-git-send-email-anton.nefedov@virtuozzo.com> From: Anton Nefedov Message-ID: Date: Thu, 21 Sep 2017 20:16:38 +0300 MIME-Version: 1.0 In-Reply-To: <1501597152-25342-1-git-send-email-anton.nefedov@virtuozzo.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 00/15] qcow2: space preallocation and COW improvements List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, den@virtuozzo.com, kwolf@redhat.com, mreitz@redhat.com, eblake@redhat.com On 1/8/2017 5:18 PM, Anton Nefedov wrote: > > This pull request is to address a few performance problems of qcow2 format: > > 1. non cluster-aligned write requests (to unallocated clusters) explicitly > pad data with zeroes if there is no backing data. This can be avoided > and the whole clusters are preallocated and zeroed in a single > efficient write_zeroes() operation, also providing better host file > continuity > > 2. moreover, efficient write_zeroes() operation can be used to preallocate > space megabytes ahead which gives noticeable improvement on some storage > types (e.g. distributed storages where space allocation operation is > expensive) > ping? I'd send the rebased series but there are no real conflicts so /thanks, Anton