usr/src/sys/tests/benchmarks/bench-4.1/csw.c

/*
 * Context switching benchmark.
 *
 * Force system to context switch 2*nsigs
 * times by forking and exchanging signals.
 * To calculate system overhead for a context
 * switch, the signocsw program must be run
 * with nsigs.  Overhead is then estimated by
 *      t1 = time csw <n>
 *      t2 = time signocsw <n>
 *      overhead = t1 - 2 * t2;
 */
#include <signal.h>

int     sigsub();
int     otherpid;
int     nsigs;

main(argc, argv)
        char *argv[];
{
        int pid;

        if (argc < 2) {
                printf("usage: %s nsignals\n", argv[0]);
                exit(1);
        }
        nsigs = atoi(argv[1]);
        signal(SIGALRM, sigsub);
        otherpid = getpid();
        pid = fork();
        if (pid != 0) {
                otherpid = pid;
                kill(otherpid, SIGALRM);
        }
        for (;;)
                pause();
}

sigsub()
{

        signal(SIGALRM, sigsub);
        kill(otherpid, SIGALRM);
        if (--nsigs <= 0)
                exit(0);
}