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

[Richard Henderson]

On 08/20/2015 09:32 PM, Dennis Luehring wrote:
> gcc prime.c -o prime.out -lm
>
> prime.out runtime
>
> tcg-indirect: ~9.3 sec (best result)
> qemu.org-git: ~11 sec
> without-optimization: ~9.9 sec (worst result)

I presume this is integer prime factoring?

> g++ src/pugixml.cpp -g -Wall -Wextra -Werror -pedantic -std=c++0x -c -MMD -MP
>
> tcg-indirect: ~2:46.5
> qemu.org-git: ~2:51.2 (worst result)
> without-optimization: ~2:14.1 (best result)

No compiler optimization?  I wouldn't expect there to be much for tcg to 
optimize there -- dropping values to memory all the time doesn't leave much.

> stream results (STREAM version $Revision: 5.10 $)
>
> tcg-indirect: (worst result)
>
> Your clock granularity/precision appears to be 41 microseconds.
> Each test below will take on the order of 632527 microseconds.
>    (= 15427 clock ticks)
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             320.8     0.511297     0.498785     0.590214
> Scale:            187.0     0.858693     0.855465     0.863527
> Add:              218.2     1.104654     1.099698     1.110341
> Triad:            169.5     1.433273     1.416321     1.502248
>
> qemu.org-git: (best result)
>
> Your clock granularity/precision appears to be 42 microseconds.
> Each test below will take on the order of 330428 microseconds.
>     (= 7867 clock ticks)
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             771.5     0.214717     0.207377     0.244214
> Scale:            288.1     0.573320     0.555401     0.660161
> Add:              423.5     0.633523     0.566661     1.092067
> Triad:            242.9     1.053032     0.987970     1.499563
>
> without-optimization:
>
> Your clock granularity/precision appears to be 41 microseconds.
> Each test below will take on the order of 745254 microseconds.
>    (= 18176 clock ticks)
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             316.6     0.524065     0.505313     0.580103
> Scale:            200.5     0.813356     0.798024     0.840986
> Add:              243.9     1.010247     0.984025     1.119149
> Triad:            182.9     1.345601     1.312236     1.427459

These results are weird.  Unoptimized less than half the speed of mainline? 
Improving optimization (with no extra work, mind) brings the results back down?


r~