[Qemu-devel] kqemu vs Standard

[Jason Brittain]

Hi Qemu developers & users!

I'm reporting in to say that I've lightly tested Qemu/kqemu, and found it
to be significantly faster with both XP and Linux guest OSs.

I tested with the following setup:

Real Hardware: IBM Thinkpad T42p, pentium M 1.80GHz, 1GB RAM, 60G IDE HD
Host OS: Fedora Core 3 "everything" installation, very slight kernel
         reconfig changes.

Guest OS: XP Corp. SP1
----------------------

This feels noticeably faster.  Double clicking on icons works a bit better,
although it doesn't work all that well still.  Instead, I right click on
icons and select "Open".  :)  The programs run faster as well, but I'm not
sure yet how I could test how much faster.  Plus, I'm happy with it, so I
may not spend much time figuring that out.

XP boot, all the way to the desktop:
65 seconds regular
45 seconds kqemu

Also, due to other changes that were checked in either at the same time as
kqemu, or just before, I believe some bugs were fixed because some errors
I used to get running some of the software I run are now gone.


Guest OS: RedHat Linux 9, modified to run a 2.6 kernel
------------------------------------------------

This boots much faster now, as the numbers below show.

Linux boot, all the way to the text (non-graphical) login prompt:
86 seconds regular
36 seconds kqemu

Probably also due to numberous bug fixes checked in recently, my Java VM/Tomcat
installation now runs inside qemu without crashing with a HotSpot VM error.
It used to run for a bit, then crash, and there wasn't anything I could do
about it other than run a newer version of Sun's JVM.  Now, it just works.  :)
I'm not yet sure if it works in the unaccelerated mode.  I'm about to test that.
Also, in unaccelerated mode, the Java VM runs very slow versus natively.  But,
using kqemu, it's decently fast.  Fast enough to develop with it running inside
qemu.  Excellent!

A Little More About How I Tested
--------------------------------

This was all done with qemu source from CVS as of the day Fabrice
checked in kqemu.  I compiled it on FC3 like:

# ./configure
# make
# make install

So, nothing fancy there.

To switch between kqemu-accelerated, and standard (unaccelerated), all
I did was load or unload the kqemu module.  Yes, when I ran qemu with
it unloaded I did get the output warning saying the acceleration was
disabled.

Here's my real (laptop) hardware's CPU info:
# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.80GHz
stepping        : 6
cpu MHz         : 599.679
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr mce cx8 mtrr pge mca cmov pat clflush 
dts acpi mmx fxsr sse sse2 ss tm pbe est tm2
bogomips        : 1187.84

--
Jason Brittain