From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v8] virtio_blk: add discard and write zeroes support Date: Fri, 26 Oct 2018 01:26:40 -0700 Message-ID: <20181026082640.GA1147@infradead.org> References: <1528258740-6581-1-git-send-email-changpeng.liu@intel.com> <20181012210628.226361-1-dverkamp@chromium.org> <20181015092740.GA3964@infradead.org> <486afcff-a8bd-a05b-e331-e395d4d14853@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <486afcff-a8bd-a05b-e331-e395d4d14853@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Paolo Bonzini Cc: Jens Axboe , "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, Christoph Hellwig , linux-block@vger.kernel.org, Stefan Hajnoczi , Changpeng Liu List-Id: virtualization@lists.linuxfoundation.org On Fri, Oct 26, 2018 at 01:28:54AM +0200, Paolo Bonzini wrote: > On 15/10/2018 11:27, Christoph Hellwig wrote: > > There is some issues in this spec. For one using the multiple ranges > > also for write zeroes is rather inefficient. Write zeroes really should > > use the same format as read and write. > > What makes it inefficient? We require a memory allocation for each write zeroes instead of encoding the lba/len in the command.