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

[Dennis Luehring]

Am 21.08.2015 um 07:49 schrieb 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?


Aurelien Jarno extracted this code from sysbench (just for my qemu 
sparc64 tests)

#include <math.h>
unsigned long long max_prime = 2000;
void prime_test()
{
  unsigned long long c;
  unsigned long long l,t;
  unsigned long long n=0;
  /* So far we're using very simple test prime number tests in 64bit */
  for(c=3; c < max_prime; c++)
  {
    t = sqrt(c);
    for(l = 2; l <= t; l++)
      if (c % l == 0)
        break;
    if (l > t )
      n++;
  }
}
int main()
{
  int i;
  for (i = 0 ; i < 10000 ; i++)
  {
    prime_test();
  }
  return 0;
}



> > 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.


without-optimization means qemu.org-git release build + undefine 
USE_TCG_OPTIMIZATIONS in tcg/tcg.c
or what compiler do you mean?


> >
> > 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?


yep they are - it seems that the assumption of the involved developers
where speed can be improved / or slowbess comes from is not correct
how are SPARC64 benchmarks done usually?

> r~