[Qemu-devel] Parallel thread execution on QEMU

[Qemu-devel] Parallel thread execution on QEMU

[kostas kotzak]

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Hi to all and thank you for your great work!

I'm Kostas, a PhD student in Chemistry 8-) but with great interest in Computing (I finished my MSc Degree in software engineering recently).

As new and naive here I may ask a stupid question and forgive me for that.

I have collected information on QEMU performance and I understand that QEMU was designed from the beginning as one core only guest on one core only host. 

I know KVM can help if host and guest work on the same architecture but what about inter-architecture translation?

Recently more and more workarounds are being developed to bypass this restriction. Namely COREMU, PQEMU, HQEMU most of them on x86 host. Recently there is a COREMU port also for RISC/MIPS/ARM host:

Jiang, X.-W., X.-L. Chen, H.
Wang and H.-P. Chen (2014). A Parallel Full-System Emulator for Risc Architure
Host. Advances in Computer Science and its Applications. H. Y. Jeong, M.
S. Obaidat, N. Y. Yen and J. J. Park, Springer Berlin Heidelberg. 279: 1045-1052

It seems that COREMU multi-thread approach is very simple and effective. Is there a reason that QEMU org does not adopt any of these solutions? At least for the two most popular architectures x86 and ARM?

I have very little free time (due to the PhD work) but I could contribute a little bit with your guidance. I'm particularly interested on this RISC/ARM/MIPS host COREMU solution because I believe cheap RISC/ARM topbox is giving poor countries the chance to learn computing and Parallel QEMU will give them the chance to use any legacy x86 application they need to use without paying a fortune.

Please give me your feedback.
Kostas

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Re: [Qemu-devel] Parallel thread execution on QEMU

[Peter Maydell]

On 13 June 2014 13:49, kostas kotzak <ckonstantinos@yahoo.co.uk> wrote:
> It seems that COREMU multi-thread approach is very simple and effective. Is
> there a reason that QEMU org does not adopt any of these solutions? At least
> for the two most popular architectures x86 and ARM?

The short answer is "because there's a big difference between
'a research project that aims to show feasibility and run some
benchmarks' and 'a portable and robust product-quality implementation
that we could maintain and release'". So far nobody has shown
much interest in working on the latter.

thanks
-- PMM

Re: [Qemu-devel] Parallel thread execution on QEMU

[Paolo Bonzini]

Il 13/06/2014 15:21, Peter Maydell ha scritto:
> On 13 June 2014 13:49, kostas kotzak <ckonstantinos@yahoo.co.uk> wrote:
>> > It seems that COREMU multi-thread approach is very simple and effective. Is
>> > there a reason that QEMU org does not adopt any of these solutions? At least
>> > for the two most popular architectures x86 and ARM?
> The short answer is "because there's a big difference between
> 'a research project that aims to show feasibility and run some
> benchmarks' and 'a portable and robust product-quality implementation
> that we could maintain and release'". So far nobody has shown
> much interest in working on the latter.

FWIW, I hope to pick up again the work that I talked about at KVM Forum 
2013.  If completed, this should make multithreaded TCG much simpler 
(though not easy by any means).  I don't plan to work on multithreaded 
TCG myself, though.

http://www.linux-kvm.org/wiki/images/1/17/Kvm-forum-2013-Effective-multithreading-in-QEMU.pdf

Paolo