From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46155) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3nNt-00045H-TR for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:02:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a3nNo-0000nq-CH for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:02:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54758) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3nNo-0000nh-7T for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:02:24 -0500 References: <1447978868-17138-1-git-send-email-mlin@kernel.org> <56506D95.70101@redhat.com> <1448266667.18175.5.camel@hasee> <56531F5F.3050709@redhat.com> <1448925639.27669.7.camel@ssi> From: Paolo Bonzini Message-ID: <565DC48B.6030903@redhat.com> Date: Tue, 1 Dec 2015 17:02:19 +0100 MIME-Version: 1.0 In-Reply-To: <1448925639.27669.7.camel@ssi> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH 0/9] vhost-nvme: new qemu nvme backend using nvme target List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ming Lin Cc: qemu-devel@nongnu.org, Christoph Hellwig , linux-nvme@lists.infradead.org, virtualization@lists.linux-foundation.org On 01/12/2015 00:20, Ming Lin wrote: > qemu-nvme: 148MB/s > vhost-nvme + google-ext: 230MB/s > qemu-nvme + google-ext + eventfd: 294MB/s > virtio-scsi: 296MB/s > virtio-blk: 344MB/s > > "vhost-nvme + google-ext" didn't get good enough performance. I'd expect it to be on par of qemu-nvme with ioeventfd but the question is: why should it be better? For vhost-net, the answer is that more zerocopy can be done if you put the data path in the kernel. But qemu-nvme is already using io_submit for the data path, perhaps there's not much to gain from vhost-nvme... Paolo > Still tuning.