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Re: [Qemu-devel] Why is SeaBIOS used with -kernel?

From: Richard W.M. Jones
Subject: Re: [Qemu-devel] Why is SeaBIOS used with -kernel?
Date: Fri, 1 Apr 2016 19:59:02 +0100
User-agent: Mutt/1.5.20 (2009-12-10)

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
> Result: 1116.0ms ±5.0ms
> Result: 1106.6ms ±5.0ms
> 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:

Result: 1099.5ms ±3.7ms

(Since we're using -kernel, we don't care about bootorder)


Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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