Re: [Qemu-devel] Qemu speed vs vmplayer?

[it]

> On Sat, 16 Dec 2006, address@hidden wrote:
>
>>> On Fri, 15 Dec 2006, Joseph Miller wrote:
>
> [..snip..]
>
>> Malc,
>>
>> Thanks,
>> I think that this was my problem.  I didn't realize that the usb tablet
>> would cause such a slowdown.  The usb tablet is such a useful feature,
>> I'm
>> sure it is commonly used.  Maybe a warning could be provided so that
>> users
>> would know it has some performance quirks.  Maybe I can look at the code
>> and find out why it is so much slower?  Maybe this is a general usb
>> problem?
>
> You think? As in: tried with and without USB and top reports much higher
> CPU usage? In any case do not rely on top(1) too much, as mentioned in
> the post for certain CPU usage patterns Linux just does not provide a
> meaningful idleness information (which top uses).
>
> Again as mentioned in the post, i have seen 30%-40% difference between
> "real" idleness and what the kernel reports via proc, but 70% is a bit
> too much. The negative impact of USB (tablet only?) on the load was
> mentioned a few times on the ML and in private conversations with
> Anthony Liguori and since there was no progress in this area i doubt
> that there's much you can do apart from reporting the issue once again.
>
> Apparently you wont find much symphaty when reporting the speed issues
> while kqemu is active. So i'd suggest to:
>
>   a. Measure and report the difference without kqemu
>   b. Use something more reliable than top(1)
>
> --
> vale
>

Yeah, I said "I think" because I wanted to use a decent benchmark to
actually test the results.  I threw in a test against VMPlayer as well.  I
found that with USB tablet emulation, Qemu was approximately only half as
fast as it could operate without it.  I did NOT perform these tests
without KQEMU for two reasons 1) the *concept* that USB tablet emulation
slows down Qemu can be shown either way and 2) I can't stand waiting
around for hours and hours while Qemu translates code, sorry.  At this
particular time, I'm really only interested in this particular case
because I use it for production use and many non-developer users are
wanting to do the same thing.  The only major difference that I found
between Qemu+KQEMU and VMPlayer was that VMPlayer is about 4x faster when
it comes to memory access.  You can view my results at:

http://www.calcmaster.net/qemu/benchmarks-20061216/

-Joseph