Re: [PATCH v2 0/6] Introduce __mt_dup() to improve the performance of fork()

[Peng Zhang <zhangpeng.00@bytedance.com>]

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See the attachment for the slightly modified benchmark.

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/*******************************************************************************
 *  The BYTE UNIX Benchmarks - Release 3
 *          Module: spawn.c   SID: 3.3 5/15/91 19:30:20
 *
 *******************************************************************************
 * Bug reports, patches, comments, suggestions should be sent to:
 *
 *	Ben Smith, Rick Grehan or Tom Yagerat BYTE Magazine
 *	ben@bytepb.byte.com   rick_g@bytepb.byte.com   tyager@bytepb.byte.com
 *
 *******************************************************************************
 *  Modification Log:
 *  $Header: spawn.c,v 3.4 87/06/22 14:32:48 kjmcdonell Beta $
 *  August 29, 1990 - Modified timing routines (ty)
 *  October 22, 1997 - code cleanup to remove ANSI C compiler warnings
 *                     Andy Kahn <kahn@zk3.dec.com>
 *
 ******************************************************************************/
char SCCSid[] = "@(#) @(#)spawn.c:3.3 -- 5/15/91 19:30:20";
/*
 *  Process creation
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/mman.h>

volatile int stop;
unsigned long iter;

void wake_me(int seconds, void (*func)())
{
	/* set up the signal handler */
	signal(SIGALRM, func);
	/* get the clock running */
	alarm(seconds);
}

void report()
{
	fprintf(stderr,"COUNT: %lu\n", iter);
	iter = 0;
	stop = 1;
}

void spawn()
{
	int status, slave;

	while (!stop) {
		if ((slave = fork()) == 0) {
			/* slave .. boring */
			exit(0);
		} else if (slave < 0) {
			/* woops ... */
			fprintf(stderr,"Fork failed at iteration %lu\n", iter);
			perror("Reason");
			exit(2);
		} else
			/* master */
			wait(&status);
		if (status != 0) {
			fprintf(stderr,"Bad wait status: 0x%x\n", status);
			exit(2);
		}
		iter++;
	}
}

int main(int argc, char	*argv[])
{
	int duration, nr_vmas = 0;
	size_t size;
	void *addr;

	if (argc != 2) {
		fprintf(stderr,"Usage: %s duration \n", argv[0]);
		exit(1);
	}
	duration = atoi(argv[1]);

	size = 10 * getpagesize();
	for (int i = 0; i <= 7000; ++i) {
		if (i == nr_vmas) {
			stop = 0;
			fprintf(stderr,"VMAs: %d\n", i);
			wake_me(duration, report);
			spawn();
			if (nr_vmas == 0)
				nr_vmas = 100;
			else nr_vmas *= 2;
		}
		addr = mmap(NULL, size, i & 1 ? PROT_READ : PROT_WRITE,
			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

		if (addr == MAP_FAILED) {
			perror("mmap");
			exit(2);
		}
	}
}