/*
 * contswap benchmark
 */

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

#define MEMORY		(1650 << 20)
#define RECLAIMERS	128

#define PAGE_SIZE	4096

#define PART		(MEMORY / RECLAIMERS)

static void *anonmap(unsigned long size)
{
	void *map = mmap(NULL, size, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
	assert(map != MAP_FAILED);
	return map;
}

static void touch_linear(char *map, unsigned long size)
{
	unsigned long off;

	for (off = 0; off < size; off += PAGE_SIZE)
		if (map[off])
			puts("huh?");
}

static void __claim(unsigned long size)
{
	char *map = anonmap(size);
	touch_linear(map, size);
	sleep(5);
	munmap(map, size);
}

static pid_t claim(unsigned long size)
{
	pid_t pid;

	switch (pid = fork()) {
	case -1:
		puts("fork failed");
		exit(1);
	case 0:
		kill(getpid(), SIGSTOP);
		__claim(size);
		exit(0);
	default:
		return pid;
	}
}

int main(void)
{
	struct timeval start, stop, diff;
	pid_t pids[RECLAIMERS];
	int nr, crap;
	char *one;

	one = anonmap(MEMORY);
	touch_linear(one, MEMORY);

	for (nr = 0; nr < RECLAIMERS; nr++)
		pids[nr] = claim(PART);
	for (nr = 0; nr < RECLAIMERS; nr++)
		kill(pids[nr], SIGCONT);
	for (nr = 0; nr < RECLAIMERS; nr++)
		waitpid(pids[nr], &crap, 0);

	gettimeofday(&start, NULL);
	touch_linear(one, MEMORY);
	gettimeofday(&stop, NULL);
	munmap(one, MEMORY);

	timersub(&stop, &start, &diff);
	printf("%lu.%lu\n", diff.tv_sec, diff.tv_usec);

	return 0;
}