Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do to speedup the emulation?

[Karel Gardas]

On Tue, Jul 28, 2015 at 9:52 AM, Dennis Luehring <address@hidden> wrote:
> (i've posted the question already on address@hidden but was toled
> to better use this mailing list)
>
> i've prepared an Debian 7.8.0 image for SPARC64/qemu emulation for C/C++
> development before-real-hardware big-endian/unaligned tests
>
> i've benchmarked compiling of single pugixml.cpp
> (https://github.com/zeux/pugixml/blob/master/src/pugixml.cpp)
>
> qemu-system-sparc64: >180sek
> x64 native : ~ 2sek

Artyom is interested in native SPARC speed, here are my bits:
Solaris 11.2 + GNU C++ 4.8.2 on both E5-2620 and T1 1GHz

- x64: 2.1s
- sparc: 17.7s

everything like with your current git, I've just cloned, run gmake and
copied command line so this is:
g++ src/pugixml.cpp -g -Wall -Wextra -Werror -pedantic -std=c++0x -c
-MMD -MP -o build/make-g++-debug-standard/src/pugixml.cpp.o

numbers average from 3-4 runs. Also this is *cheap* T1, with current
state of the art SPARC you can get way much better numbers I'm sure,
even cheap M4000 should be way better. Anyway this is just for the
reference.

Last note: few months ago I've been discussing with some
Qemu/SPARC64/Debian guys about qemu/sparc64 slowness. The discussion
was started by me when I've compared numbers (compilation performance
with GNU C like you do here) on qemu-sparc64 and on qemu-aarch64 and
they were way much different. I used nbnech2 for benchmarking qemu
emulation and time make nbench2 for benchmarking compilation speed.
What was interesting was that nbench2 was comparable on aarch64 and
sparc64 but time make was completely off (sparc much slower)  I also
provided few profile runs but the conclusion from this time is that
perhaps sparc is hard due to its MMU, I don't remember well. If
anybody is interested I can dig those old emails. IIRC I've used Qemu
2.2.0 for this benchmarking so not that old.

Thanks,
Karel