40 lines
847 B
C
40 lines
847 B
C
#include <stdio.h>
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#include <time.h>
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int identity(int x) { return x; }
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int sum(int s)
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{
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int i;
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for(i=0; i < 1000000; i++) s += i;
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return s;
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}
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#ifdef CLOCK_PROCESS_CPUTIME_ID
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/* cpu time in the current process */
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#define CLOCKTYPE CLOCK_PROCESS_CPUTIME_ID
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#else
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/* this one should be appropriate to avoid errors on multiprocessors systems */
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#define CLOCKTYPE CLOCK_MONOTONIC
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#endif
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double time_it(int (*action)(int), int arg)
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{
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struct timespec tsi, tsf;
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clock_gettime(CLOCKTYPE, &tsi);
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action(arg);
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clock_gettime(CLOCKTYPE, &tsf);
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double elaps_s = difftime(tsf.tv_sec, tsi.tv_sec);
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long elaps_ns = tsf.tv_nsec - tsi.tv_nsec;
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return elaps_s + ((double)elaps_ns) / 1.0e9;
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}
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int main()
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{
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printf("identity (4) takes %lf s\n", time_it(identity, 4));
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printf("sum (4) takes %lf s\n", time_it(sum, 4));
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return 0;
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}
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