From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50582) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am4T9-0007xs-3U for qemu-devel@nongnu.org; Fri, 01 Apr 2016 15:10:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1am4T5-0006cm-3H for qemu-devel@nongnu.org; Fri, 01 Apr 2016 15:10:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58864) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am4T4-0006ce-R5 for qemu-devel@nongnu.org; Fri, 01 Apr 2016 15:10:51 -0400 Date: Fri, 1 Apr 2016 20:10:48 +0100 From: "Richard W.M. Jones" Message-ID: <20160401191048.GF19398@redhat.com> References: <1459502310.7011.37.camel@redhat.com> <20160401101733.GI32728@redhat.com> <1459508875.7011.62.camel@redhat.com> <20160401111139.GK32728@redhat.com> <1459510371.7011.63.camel@redhat.com> <20160401114947.GM32728@redhat.com> <20160401153540.GD25490@morn.lan> <20160401184131.GP32728@redhat.com> <20160401185902.GE19398@redhat.com> <20160401190415.GA13599@morn.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20160401190415.GA13599@morn.lan> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] Why is SeaBIOS used with -kernel? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin O'Connor Cc: marc.mari.barcelo@gmail.com, Paolo Bonzini , Gerd Hoffmann , qemu-devel@nongnu.org, Stefan Hajnoczi On Fri, Apr 01, 2016 at 03:04:15PM -0400, Kevin O'Connor wrote: > On Fri, Apr 01, 2016 at 07:59:02PM +0100, Richard W.M. Jones wrote: > > On Fri, Apr 01, 2016 at 07:41:31PM +0100, Richard W.M. Jones wrote: > > > Below are some benchmarks of the other things you mentioned. These > > > are complete appliance boot-to-shutdown times [*not* just SeaBIOS]. > > > All debugging has been disabled, and I'm using a slightly different > > > kernel version, so these runs are not comparable to earlier results= I > > > posted. All times are the mean of 10 runs. The =B1 number is 1 > > > standard deviation from the mean. > > >=20 > > > In my estimation only CONFIG_FW_ROMFILE_LOAD=3Dn seems to make a > > > measurable difference. > > >=20 > > > -------------------------------------------------------------------= --- > > > Ordinary qemu SeaBIOS configuration > > > Result: 1227.5ms =B17.7ms > > >=20 > > > -bios boot-fast.bin, as per my previous patch > > > Result: 1113.7ms =B16.4ms > > >=20 > > > Leaving CONFIG_XEN and CONFIG_THREADS at default settings > > > Result: 1111.2ms =B13.8ms > > >=20 > > > CONFIG_USE_SMM=3Dn > > > Result: 1116.0ms =B15.0ms > > >=20 > > > CONFIG_FW_ROMFILE_LOAD=3Dn > > > Result: 1106.6ms =B15.0ms > > >=20 > > > CONFIG_RELOCATE_INIT=3Dn > > > Result: 1104.7ms =B111.2ms > > > -------------------------------------------------------------------= --- > >=20 > > Actually, CONFIG_RELOCATE_INIT=3Dn looks like it is doing something, = but > > the error bars are quite large. > >=20 > > Here's another one that makes a difference: > >=20 > > CONFIG_BOOTORDER=3Dn > > Result: 1099.5ms =B13.7ms >=20 > Are you sure you had CONFIG_DEBUG_LEVEL=3D0? Yes, I'm pretty sure. I'm using qemu with -bios bios-fast.bin, and recompiling SeaBIOS under qemu each time (make && make -C roms bios). The test program is: https://github.com/libguestfs/libguestfs/commit/96ce2f9afedc6a7ecb2f77819= 58c3940255f453b > Otherwise, it doesn't make > sense that disabling CONFIG_BOOTORDER=3Dn would change the boot time. Could it be explained by it avoiding slow access to qemu fw_cfg? > Disabling CONFIG_DEBUG_SERIAL is not enough, because SeaBIOS also > writes to port 0x402 as an internal debugging mechanism. Rich. --=20 Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rj= ones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v