Re: [Pharo-users] [Stupid Benchmarks] C++ vs Pharo

Dec. 17, 2016


      
...
On 17 Dec 2016, at 15:23, Sven Van Caekenberghe <sven@stfx.eu> wrote:
...
On 17 Dec 2016, at 14:28, Henrik Nergaard <henrik.nergaard@uia.no> wrote:
This is not a comparable benchmark as the sum in Smalltalk keeps on growing and ends up doing LargeInteger calculations and thus the speed loss, while the c the int just rolls over.
Sum in Smalltalk = 500000000500000000
Sum in C   = -1243309312
Yes, I realised afterwards. Shame on me.
Now, in Pharo 64 bits:
[ 
  | sum | 
  sum:= 0. 
  1 to: 1e9 do: [ :i | sum := sum + i ]. 
  self assert: sum = (1e9 * (1e9 + 1) / 2) ] timeToRun.
"0:00:00:03.379"
(1e9 * (1e9 + 1) / 2) < SmallInteger maxVal.
"true"
So there the speed difference is way smaller.
And here is a correct C99 version

$ cat bench.c 
#include <stdio.h>
#include <time.h>
#include <assert.h>

int main() {
  clock_t begin = clock();

  long sum = 0;
  for (int i = 1; i <= 1000000000; i++)
    sum += i;

  assert(sum == ((1000000000*1000000001)/2));

  clock_t end = clock();
  double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
  printf("time_spent=%f\n", time_spent);
}

prometheus:tmp sven$ ./a.out 
time_spent=2.393986
...
...
Best regards,
Henrik
-----Original Message-----
From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] On Behalf Of Sven Van Caekenberghe
Sent: Saturday, December 17, 2016 2:15 PM
To: Any question about pharo is welcome <pharo-users@lists.pharo.org>
Subject: Re: [Pharo-users] [Stupid Benchmarks] C++ vs Pharo
Like this:
[ | sum | sum:= 0. 1 to: 1e9 do: [ :i | sum := sum + i ]. sum ] timeToRun.
"0:00:00:39.305"
cat bench.c
#include <stdio.h>
#include <time.h>
int main() {
clock_t begin = clock();
int sum = 0;
for (int i = 0; i < 1000000000; i++)
  sum += i;
clock_t end = clock();
double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf("time_spent=%f\n", time_spent); }
./a.out
time_spent=2.370234
That is C being 16 times faster ...
...
On 17 Dec 2016, at 13:49, Sven Van Caekenberghe <sven@stfx.eu> wrote:
Hmm, this sounds wrong (C++ should be (a lot) faster on such micro benchmarks).
You should exclude the executable startup time.
In Pharo you should do [ .. ] timeToRun and something similar in C/C++.
...
On 17 Dec 2016, at 13:41, Dimitris Chloupis <kilon.alios@gmail.com> wrote:
in multiplication pharo is around 2 times slower compared to C++
#include <stdio.h>
int main()
{
double x=1;
for(double i; i<1000000000 ; ++i)
 {
 x = 0.1*i;
 }
return 1;
}
time ./testMul
     3.13 real         3.13 user         0.00 sys
time ./pharo Ephestos.image eval "|x| x := 1. 1 to: 1000000000 do:[:each| x := 0.1 * each]"
1
     4.97 real         4.48 user         0.09 sys
On Sat, Dec 17, 2016 at 2:16 PM Dimitris Chloupis <kilon.alios@gmail.com> wrote:
So I was bored and decided to test how fast pharo is compared to C++.
so I tested addition
C++ version:
#include <stdio.h>
int main()
{
double x=0;
while(x<1000000000)
 {
 x = x+1;
 }
return 1;
}
time ./test1
     2.84 real         2.84 user         0.00 sys
Pharo version:
time ./pharo Ephestos.image eval "|x| x := 0. 1 to: 1000000000 do:[:each| x := x +1]"
1
     2.09 real         1.94 user         0.08 sys
Pharo is +50% faster than C++ ... o_O ... that's suprising, I assume here Pharo VM probably does some kind of optimisation.