mirror of https://github.com/t1meshift/os_labs.git
73 lines
2.8 KiB
C
73 lines
2.8 KiB
C
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/******************************************************************
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* CACHE project *
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* *
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* Using this program, on as many different kinds of computers as *
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* possible, investigate these cache parameters: *
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* -- total cache size *
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* -- cache width *
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* -- cache replacement policy *
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******************************************************************/
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/* I got this program from Brian Harvey, who teaches CS61C at
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Berkeley. He didn't put a copyright on it, but he should
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at least get credit for it. Thanks, Brian! */
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/times.h>
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#include <sys/types.h>
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#include <time.h>
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#define CACHE_MIN (32*1024) /* smallest cache */
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#define CACHE_MAX (32*1024*1024) /* largest cache */
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#define SAMPLE 10 /* to get a larger time sample */
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int x[CACHE_MAX]; /* array going to stride through */
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long clk_tck;
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double get_seconds() { /* routine to read time */
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struct tms rusage;
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times(&rusage); /* UNIX utility: time in clock ticks */
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return (double) (rusage.tms_utime)/clk_tck;
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}
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int main() {
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int register i, index, stride, limit, temp;
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int steps, tsteps, csize;
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double sec0, sec; /* timing variables */
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clk_tck = sysconf(_SC_CLK_TCK);
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for (csize=CACHE_MIN; csize <= CACHE_MAX; csize=csize*2)
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for (stride=1; stride <= csize/2; stride=stride*2) {
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sec = 0; /* initialize timer */
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limit = csize-stride+1; /* cache size this loop */
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steps = 0;
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do { /* repeat until collect 1 second */
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sec0 = get_seconds(); /* start timer */
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for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
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for (index=0; index < limit; index=index+stride)
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x[index] = x[index] + 1; /* cache access */
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steps = steps + 1; /* count while loop iterations */
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sec = sec + (get_seconds() - sec0);/* end timer */
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} while (sec < 1.0); /* until collect 1 second */
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/* Repeat empty loop to loop subtract overhead */
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tsteps = 0; /* used to match no. while iterations */
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do { /* repeat until same no. iterations as above */
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sec0 = get_seconds(); /* start timer */
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for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
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for (index=0; index < limit; index=index+stride)
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temp = temp + index; /* dummy code */
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tsteps = tsteps + 1; /* count while iterations */
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sec = sec - (get_seconds() - sec0);/* - overhead */
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} while (tsteps<steps); /* until = no. iterations */
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printf("Size: %7ld Stride: %7ld read+write: %4.4lf ns\n",
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csize*sizeof(int), stride*sizeof(int),
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(double) sec*1e9/(steps*SAMPLE*stride*((limit-1)/stride+1)));
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}; /* end of both outer for loops */
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}
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