MemEval.py

#!/usr/bin/python

import operator
import time

KB = 1024
MB = KB**2
GB = MB*KB

INT_SIZE = 4;

ARRAY_MIN = KB
ARRAY_MAX = (KB*4)**2

x = [0]*ARRAY_MAX

def step_range(start, end, step, step_func, compare_func):
    while compare_func(start, end):
        yield start
        start = step_func(start, step)

def getSeconds():
    return time.time()

def label(i):
    if i < 1e3:
        print '%1dB,'%(i),
    elif i < 1e6:
        print '%1dK,'%(i / KB),
    elif i < 1e9:
        print '%1dM,'%(i / MB),
    else:
        print '%1dG,'%(i / GB),

def main():
    print ' ,',
    for stride in step_range(1, ARRAY_MAX / 2, 2, operator.mul, operator.le):
        label(int(stride*INT_SIZE))
    print

    # Main loop for each configuration
    for csize in step_range(ARRAY_MIN, ARRAY_MAX, 2, operator.mul, operator.le):
        label(int(csize * INT_SIZE)) #Print cache size for this loop
        for stride in step_range(1, csize / 2, 2, operator.mul, operator.le):
            # Layout path of memory references in array
            for index in step_range(0, csize, stride, operator.add, operator.lt):
                x[index] = index + stride
            x[index - stride] = 0

            ###print '[Stride='+str(stride)+']'
            ###print '',

            # Wait for timer to roll over
            lastsec = getSeconds()
            while True:
                sec0 = getSeconds()
                if long(sec0) != long(lastsec):
                    break

            # Walk through path in array for twenty seconds
            # This gives 5% accuracy with second resolution
            steps = 0.0; # Number of steps taken
            nextstep = 0; # Start at beginning of path
            sec0 = getSeconds() # Start timer
            while True: # Repeat for 20 seconds
                for i in step_range(stride, 0, 1, operator.sub, operator.ne): # Keep sample size
                    nextstep = 0
                    while True:
                        nextstep = x[nextstep]
                        if nextstep == 0:
                            break
                steps += 1
                sec1 = getSeconds()
                if (sec1 - sec0) >= 20.0:
                    break
            sec = sec1 - sec0;

            # Repeat empty loop to loop subtracted overhead
            tsteps = 0.0; # used to match no. while iterations
            sec0 = getSeconds() # Start timer
            while True:
                for i in step_range(stride, 0, 1, operator.sub, operator.ne): # Keep sample size
                    index = 0;
                    while True:
                        index += stride
                        if index >= csize:
                            break
                tsteps += 1
                sec1 = getSeconds()
                if tsteps >= steps:
                    break
            sec -= (sec1 - sec0)
            loadtime = (sec * 1e9) / (steps * csize)

            # Write out results in CSV format
            val = 0.1 if loadtime < 0.1 else loadtime
            print '%4.1f,'%(val),
        print

if __name__ == '__main__':
    main()