i386 vs amd64 (32 bit vs 64 bit)

matteo@matteo-notebook:~/src/benchs$ make CFLAGS='-O3 -m32'
cc -O3 -m32 -DUNIX flops.c -o flops -Wall
cc -O3 -m32 -c dry.c -o dry1.o -Wall
cc -O3 -m32 -DPASS2 dry.c dry1.o -o dry -Wall
matteo@matteo-notebook:~/src/benchs$ ./flops

   FLOPS C Program (Double Precision), V2.0 18 Dec 1992

   Module     Error        RunTime      MFLOPS
                            (usec)
     1      2.8434e-13      0.0109   1279.4281
     2      1.4704e-15      0.0086    810.0493
     3     -3.8213e-15      0.0072   2360.3415
     4      6.1151e-14      0.0078   1921.7940
     5     -4.4419e-14      0.0128   2260.3219
     6      7.7002e-15      0.0123   2355.5949
     7     -6.4690e-13      0.0329    364.3069
     8      2.2789e-14      0.0133   2259.5619

   Iterations      =  512000000
   NullTime (usec) =     0.0000
   MFLOPS(1)       =  1031.5497
   MFLOPS(2)       =   831.2910
   MFLOPS(3)       =  1500.4019
   MFLOPS(4)       =  2241.6233

matteo@matteo-notebook:~/src/benchs$ ./dry 2>/dev/null

Dhrystone Benchmark, Version C, Version 2.2
Program compiled without 'register' attribute
Using times(), HZ=100

Trying 50000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 500000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 5000000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 50000000 runs through Dhrystone:
Microseconds for one run through Dhrystone:        0.1
Dhrystones per Second:                        16025641

matteo@matteo-notebook:~/src/benchs$ make clean
rm -f flops dry *.o
matteo@matteo-notebook:~/src/benchs$ make CFLAGS='-O3'
cc -O3 -DUNIX flops.c -o flops -Wall
cc -O3 -c dry.c -o dry1.o -Wall
cc -O3 -DPASS2 dry.c dry1.o -o dry -Wall
matteo@matteo-notebook:~/src/benchs$ ./flops

   FLOPS C Program (Double Precision), V2.0 18 Dec 1992

   Module     Error        RunTime      MFLOPS
                            (usec)
     1      4.0146e-13      0.0100   1397.5308
     2     -1.4166e-13      0.0082    850.2625
     3      4.7184e-14      0.0065   2618.2720
     4     -1.2557e-13      0.0059   2524.3387
     5     -1.3800e-13      0.0124   2338.2305
     6      3.2380e-13      0.0118   2466.4038
     7     -8.4583e-11      0.0301    398.2497
     8      3.4867e-13      0.0125   2394.2788

   Iterations      =  512000000
   NullTime (usec) =     0.0000
   MFLOPS(1)       =  1091.1397
   MFLOPS(2)       =   909.4140
   MFLOPS(3)       =  1635.3977
   MFLOPS(4)       =  2478.0204

matteo@matteo-notebook:~/src/benchs$ ./dry 2>/dev/null

Dhrystone Benchmark, Version C, Version 2.2
Program compiled without 'register' attribute
Using times(), HZ=100

Trying 50000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 500000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 5000000 runs through Dhrystone:
Measured time too small to obtain meaningful results

Trying 50000000 runs through Dhrystone:
Microseconds for one run through Dhrystone:        0.0
Dhrystones per Second:                        21097046

matteo@matteo-notebook:~/src/xz-5.2.1$ time sudo schedtool -F -p 99 -n -19 -e ./xz32 -v -9fk linux-4.1.2.tar
linux-4.1.2.tar (1/1)
  100 %        78,9 MiB / 568,3 MiB = 0,139   1,2 MiB/s       7:52

real    7m52.261s
user    7m51.049s
sys     0m0.678s
matteo@matteo-notebook:~/src/xz-5.2.1$ time sudo schedtool -F -p 99 -n -19 -e ./xz64 -v -9fk linux-4.1.2.tar
linux-4.1.2.tar (1/1)
  100 %        78,9 MiB / 568,3 MiB = 0,139   1,3 MiB/s       7:02

real    7m2.905s
user    7m1.774s
sys     0m0.653s