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Re: [Qemu-devel] Why is SeaBIOS used with -kernel?
From: |
Kevin O'Connor |
Subject: |
Re: [Qemu-devel] Why is SeaBIOS used with -kernel? |
Date: |
Fri, 1 Apr 2016 15:04:15 -0400 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
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 ± number is 1
> > standard deviation from the mean.
> >
> > In my estimation only CONFIG_FW_ROMFILE_LOAD=n seems to make a
> > measurable difference.
> >
> > ----------------------------------------------------------------------
> > Ordinary qemu SeaBIOS configuration
> > Result: 1227.5ms ±7.7ms
> >
> > -bios boot-fast.bin, as per my previous patch
> > Result: 1113.7ms ±6.4ms
> >
> > Leaving CONFIG_XEN and CONFIG_THREADS at default settings
> > Result: 1111.2ms ±3.8ms
> >
> > CONFIG_USE_SMM=n
> > Result: 1116.0ms ±5.0ms
> >
> > CONFIG_FW_ROMFILE_LOAD=n
> > Result: 1106.6ms ±5.0ms
> >
> > CONFIG_RELOCATE_INIT=n
> > Result: 1104.7ms ±11.2ms
> > ----------------------------------------------------------------------
>
> Actually, CONFIG_RELOCATE_INIT=n looks like it is doing something, but
> the error bars are quite large.
>
> Here's another one that makes a difference:
>
> CONFIG_BOOTORDER=n
> Result: 1099.5ms ±3.7ms
Are you sure you had CONFIG_DEBUG_LEVEL=0? Otherwise, it doesn't make
sense that disabling CONFIG_BOOTORDER=n would change the boot time.
Disabling CONFIG_DEBUG_SERIAL is not enough, because SeaBIOS also
writes to port 0x402 as an internal debugging mechanism.
-Kevin
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, (continued)
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Gerd Hoffmann, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Paolo Bonzini, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?,
Kevin O'Connor <=
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/02
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Paolo Bonzini, 2016/04/02
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01