From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60704) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bG4A8-0002Bb-PG for qemu-devel@nongnu.org; Thu, 23 Jun 2016 08:55:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bG4A4-0000CU-JN for qemu-devel@nongnu.org; Thu, 23 Jun 2016 08:55:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39661) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bG4A4-0000Bv-DT for qemu-devel@nongnu.org; Thu, 23 Jun 2016 08:55:12 -0400 Date: Thu, 23 Jun 2016 13:55:06 +0100 From: "Daniel P. Berrange" Message-ID: <20160623125506.GO17868@redhat.com> Reply-To: "Daniel P. Berrange" References: <1466151257-96318-1-git-send-email-chao.p.peng@linux.intel.com> <20160619035104.GA13650@redhat.com> <20160620061217.GF21465@pengc-linux.bj.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160620061217.GF21465@pengc-linux.bj.intel.com> Subject: Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chao Peng Cc: "Michael S. Tsirkin" , Haozhong Zhang , Xiao Guangrong , Eduardo Habkost , qemu-devel@nongnu.org, Paolo Bonzini , gor Mammedov , Richard Henderson On Mon, Jun 20, 2016 at 02:12:17PM +0800, Chao Peng wrote: > On Sun, Jun 19, 2016 at 06:51:04AM +0300, Michael S. Tsirkin wrote: > > On Fri, Jun 17, 2016 at 04:14:08AM -0400, Chao Peng wrote: > > > - it is FAST; > > > > Any numbers to demonstrate just how fast it is and fast at what? > > On a 2.30GHz Haswell server, guest kernel booting time is 59.9ms by > following test steps listed at > > https://github.com/chao-p/qemu-lite-tools > > Ran the same test with "-machine q35", the guest kernel booting > time is 129.8ms. There is additional 75ms in SeaBIOS for Q35 case. I think it'd be useful / interesting to understand why we have saved this time vs Q35. I'm not a huge fan of the idea of defining an arbitrarily cut down machine type, because inevitably one applications view of what is the "bare minimum required functionality" will be different from another applications' view. It seems to me that whether some features emulated by QEMU are slow or not should only matter if the guest OS actually tries to use those features. IOW, could we achieve the same speed up in boot time, by making Linux more configurable at runtime. eg so with a single Linux kernel binary and standard Q35/PIIX machine type, we can disable slow functionality by just giving Linux suitable kernel command line arguments. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|