75 lines
1.6 KiB
C
75 lines
1.6 KiB
C
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/*
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* test minimum select time
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*
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* ./prog usec [method [duration]]
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/time.h>
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#include <poll.h>
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#include <inttypes.h>
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enum { M_SELECT =0 , M_POLL, M_USLEEP };
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static const char *names[] = { "select", "poll", "usleep" };
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int
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main(int argc, char *argv[])
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{
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struct timeval ta, tb, prev;
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int usec = 1, total = 0, method = M_SELECT;
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uint32_t *vals = NULL;
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uint32_t i, count = 0;
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#define LIM 1000000
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if (argc > 1)
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usec = atoi(argv[1]);
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if (usec <= 0)
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usec = 1;
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else if (usec > 500000)
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usec = 500000;
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if (argc > 2) {
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if (!strcmp(argv[2], "poll"))
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method = M_POLL;
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else if (!strcmp(argv[2], "usleep"))
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method = M_USLEEP;
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}
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if (argc > 3)
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total = atoi(argv[3]);
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if (total < 1)
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total = 1;
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else if (total > 10)
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total = 10;
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fprintf(stderr, "testing %s for %dus over %ds\n",
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names[method], usec, total);
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gettimeofday(&ta, NULL);
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prev = ta;
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vals = calloc(LIM, sizeof(uint32_t));
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for (;;) {
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if (method == M_SELECT) {
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struct timeval to = { 0, usec };
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select(0, NULL, NULL, NULL, &to);
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} else if (method == M_POLL) {
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poll(NULL, 0, usec/1000);
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} else {
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usleep(usec);
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}
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gettimeofday(&tb, NULL);
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timersub(&tb, &prev, &prev);
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if (count < LIM)
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vals[count] = prev.tv_usec;
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count++;
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prev = tb;
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timersub(&tb, &ta, &tb);
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if (tb.tv_sec > total)
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break;
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}
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fprintf(stderr, "%dus actually took %dus\n",
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usec, (int)(tb.tv_sec * 1000000 + tb.tv_usec) / count );
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for (i = 0; i < count && i < LIM; i++)
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fprintf(stdout, "%d\n", vals[i]);
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return 0;
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}
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