On Aug 12, 2016, at 9:19 AM, Alex Bennée wrote:
On 11 August 2016 at 17:43, G 3 <programmingk...@gmail.com> wrote:
On Aug 11, 2016, at 11:24 AM, qemu-devel-requ...@nongnu.org wrote:
Performance
===========
You can't do full work-load testing on this tree due to the lack of
atomic support (but I will run some numbers on
mttcg/base-patches-v4-with-cmpxchg-atomics-v2). However you certainly
see a run time improvement with the kvm-unit-tests TCG group.
retry.py called with ['./run_tests.sh', '-t', '-g', 'tcg', '-o',
'-accel
tcg,thread=single']
run 1: ret=0 (PASS), time=1047.147924 (1/1)
run 2: ret=0 (PASS), time=1071.921204 (2/2)
run 3: ret=0 (PASS), time=1048.141600 (3/3)
Results summary:
0: 3 times (100.00%), avg time 1055.737 (196.70 varience/14.02
deviation)
Ran command 3 times, 3 passes
retry.py called with ['./run_tests.sh', '-t', '-g', 'tcg', '-o',
'-accel
tcg,thread=multi']
run 1: ret=0 (PASS), time=303.074210 (1/1)
run 2: ret=0 (PASS), time=304.574991 (2/2)
run 3: ret=0 (PASS), time=303.327408 (3/3)
Results summary:
0: 3 times (100.00%), avg time 303.659 (0.65 varience/0.80
deviation)
Ran command 3 times, 3 passes
The TCG tests run with -smp 4 on my system. While the TCG tests are
purely CPU bound they do exercise the hot and cold paths of TCG
execution (especially when triggering SMC detection). However
there is
still a benefit even with a 50% overhead compared to the ideal 263
second elapsed time.
Alex
Your tests results look very promising. It looks like you saw a 3x
speed
improvement over single threading. Excellent. I wonder what the
numbers
would be for a 22 core Xeon or 72 core Xeon Phi...
Well the initial results look like they tail off but I need to test
on a more
capable machine. I'm going to package up the test case first so people
can easily
replicate the test.
Do you think you could some test with an x86 guest like Windows
XP? There
are plenty of benchmark tests for this platform. Video encoding,
Youtube
video playback, and number crunching programs' results would be very
interesting to see.
I don't have any Windows images to hand I'm afraid. Besides Windows
is a fairly
boring guest from this point of view because:
- it's x86, so why use TCG over KVM
- QEMU TCG generally sucks at media bencmarks due to SIMD emulation
Mac OS X host don't have a hypervisor that QEMU supports (VirtualBox
isn't supported), so TCG is the only thing that can be used. Maybe a
free x86 guest like Linux could be used?