From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753838Ab2GXM3j (ORCPT ); Tue, 24 Jul 2012 08:29:39 -0400 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:44464 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753336Ab2GXM3i (ORCPT ); Tue, 24 Jul 2012 08:29:38 -0400 Message-ID: <500E954F.8090102@gmail.com> Date: Tue, 24 Jul 2012 14:30:07 +0200 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120713 Thunderbird/13.0 MIME-Version: 1.0 To: dlaor@redhat.com CC: Rusty Russell , mst@redhat.com, penberg@kernel.org, asias.hejun@gmail.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, avi@redhat.com, anthony@codemonkey.ws, wency@cn.fujitsu.com Subject: Re: [RFC 0/2] virtio: provide a way for host to monitor critical events in the device References: <1343075561-29316-1-git-send-email-levinsasha928@gmail.com> <87a9yprc4v.fsf@rustcorp.com.au> <500E5C36.2070601@redhat.com> In-Reply-To: <500E5C36.2070601@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/24/2012 10:26 AM, Dor Laor wrote: > On 07/24/2012 07:55 AM, Rusty Russell wrote: >> On Mon, 23 Jul 2012 22:32:39 +0200, Sasha Levin wrote: >>> As it was discussed recently, there's currently no way for the guest to notify >>> the host about panics. Further more, there's no reasonable way to notify the >>> host of other critical events such as an OOM kill. >> >> I clearly missed the discussion. Is this actually useful? In practice, > > Admit this is not a killer feature.. > >> won't you want the log from the guest? What makes a virtual guest >> different from a physical guest? > > Most times virt guest can do better than a physical OS. In that sense, this is where virtualization shines (live migration, hotplug for any virtual resource including net/block/cpu/memory/..). > > There are plenty of niche but worth while small features such as the virtio-trace series and other that allow the host/virt-mgmt to get more insight into the guest w/o a need to configure the guest. > > In theory guest OOM can trigger a host memory hot plug action. Again, I don't see it as a key feature.. > >> >> Guest watchdog functionality might be useful, but that's simpler to > > There is already a fully emulated watchdog device in qemu. There is, but why emulate physical devices when you can take advantage of virtio? You could say the same about the rest of the virtio family - "There is already a fully emulated NIC device in qemu". From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [RFC 0/2] virtio: provide a way for host to monitor critical events in the device Date: Tue, 24 Jul 2012 14:30:07 +0200 Message-ID: <500E954F.8090102@gmail.com> References: <1343075561-29316-1-git-send-email-levinsasha928@gmail.com> <87a9yprc4v.fsf@rustcorp.com.au> <500E5C36.2070601@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: wency@cn.fujitsu.com, kvm@vger.kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, penberg@kernel.org, avi@redhat.com, anthony@codemonkey.ws To: dlaor@redhat.com Return-path: In-Reply-To: <500E5C36.2070601@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 List-Id: kvm.vger.kernel.org On 07/24/2012 10:26 AM, Dor Laor wrote: > On 07/24/2012 07:55 AM, Rusty Russell wrote: >> On Mon, 23 Jul 2012 22:32:39 +0200, Sasha Levin wrote: >>> As it was discussed recently, there's currently no way for the guest to notify >>> the host about panics. Further more, there's no reasonable way to notify the >>> host of other critical events such as an OOM kill. >> >> I clearly missed the discussion. Is this actually useful? In practice, > > Admit this is not a killer feature.. > >> won't you want the log from the guest? What makes a virtual guest >> different from a physical guest? > > Most times virt guest can do better than a physical OS. In that sense, this is where virtualization shines (live migration, hotplug for any virtual resource including net/block/cpu/memory/..). > > There are plenty of niche but worth while small features such as the virtio-trace series and other that allow the host/virt-mgmt to get more insight into the guest w/o a need to configure the guest. > > In theory guest OOM can trigger a host memory hot plug action. Again, I don't see it as a key feature.. > >> >> Guest watchdog functionality might be useful, but that's simpler to > > There is already a fully emulated watchdog device in qemu. There is, but why emulate physical devices when you can take advantage of virtio? You could say the same about the rest of the virtio family - "There is already a fully emulated NIC device in qemu".