main.c

/*
 * Copyright (C) 2010 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#define _GNU_SOURCE
#include <sched.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <hwloc.h>
#include <hwloc/glibc-sched.h>
#include <sys/types.h>
#include <signal.h>

#define MAX_TASKS 1024
#define CACHELINE_SIZE 128
#define WARMUP_ITERATIONS 5

extern char *testcase_description;
extern void __attribute__((weak)) testcase_prepare(void) { }
extern void __attribute__((weak)) testcase_cleanup(void) { }
extern void *testcase(void *iterations);

static char *initialise_shared_area(unsigned long size)
{
	char template[] = "/tmp/shared_area_XXXXXX";
	int fd;
	char *m;
	int page_size = getpagesize();

	/* Align to page boundary */
	size = (size + page_size-1) & ~(page_size-1);

	fd = mkstemp(template);
	if (fd < 0) {
		perror("mkstemp");
		exit(1);
	}

	if (ftruncate(fd, size) == -1) {
		perror("ftruncate");
		unlink(template);
		exit(1);
	}

	m = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (m == MAP_FAILED) {
		perror("mmap");
		unlink(template);
		exit(1);
	}

	memset(m, 0, size);

	unlink(template);

	return m;
}

static void usage(char *command)
{
	printf("Usage: %s <-t tasks> <-s iterations>\n\n", command);
	exit(1);
}

#ifdef THREADS

#include <pthread.h>

void new_task(void *(func)(void *), void *arg)
{
	pthread_t tid;

	pthread_create(&tid, NULL, func, arg);
}

void new_task_affinity(void *(func)(void *), void *arg,
		       size_t cpuset_size, cpu_set_t *mask)
{
	pthread_attr_t attr;
	pthread_t tid;

	pthread_attr_init(&attr);

	pthread_attr_setaffinity_np(&attr, cpuset_size, mask);

	pthread_create(&tid, &attr, func, arg);

	pthread_attr_destroy(&attr);
}

/* All threads will die when we exit */
static void kill_tasks(void)
{
}

#else
#include <signal.h>

static int pids[MAX_TASKS];
static int nr_pids;

/* Watchdog used to make sure all children exit when the parent does */
static int parent_pid;
static void watchdog(int junk)
{
	if (kill(parent_pid, 0) == -1)
		exit(0);

	alarm(1);
}

void new_task(void *(func)(void *), void *arg)
{
	int pid;

	parent_pid = getpid();

	pid = fork();
	if (pid < 0) {
		perror("fork");
		exit(1);
	}

	if (!pid) {
		struct sigaction sa;

		memset(&sa, 0, sizeof(sa));
		sa.sa_handler = watchdog;
		sa.sa_flags = SA_RESTART;
		sigaction(SIGALRM, &sa, NULL);
		alarm(1);

		func(arg);
	}

	pids[nr_pids++] = pid;
}

void new_task_affinity(void *(func)(void *), void *arg,
		       size_t cpuset_size, cpu_set_t *mask)
{
	cpu_set_t old_mask;
	int pid;

	sched_getaffinity(0, sizeof(old_mask), &old_mask);
	sched_setaffinity(0, cpuset_size, mask);

	parent_pid = getpid();

	pid = fork();
	if (pid < 0) {
		perror("fork");
		exit(1);
	}

	if (!pid) {
		struct sigaction sa;

		memset(&sa, 0, sizeof(sa));
		sa.sa_handler = watchdog;
		sa.sa_flags = SA_RESTART;
		sigaction(SIGALRM, &sa, NULL);
		alarm(1);

		func(arg);
	}

	sched_setaffinity(0, sizeof(old_mask), &old_mask);

	pids[nr_pids++] = pid;
}


static void kill_tasks(void)
{
	int i;

	for (i = 0; i < nr_pids; i++)
		kill(pids[i], SIGTERM);
}
#endif

int main(int argc, char *argv[])
{
	int opt_tasks = 1;
	int opt_iterations = 0;
	int iterations = 0;
	int i, n;
	char *m;
	static unsigned long long *results[MAX_TASKS];
	hwloc_topology_t topology;
	unsigned long long prev[MAX_TASKS] = {0, };
	unsigned long long total = 0;

	while (1) {
		signed char c = getopt(argc, argv, "t:s:h");
		if (c < 0)
			break;

		switch (c) {
			case 't':
				opt_tasks = atoi(optarg);
				if (opt_tasks > MAX_TASKS) {
					printf("tasks cannot exceed %d\n",
					       MAX_TASKS);
					exit(1);
				}
				break;

			case 's':
				opt_iterations = atoi(optarg);
				break;

			default:
				usage(argv[0]);
		}
	}

	if (optind < argc)
		usage(argv[0]);

	m = initialise_shared_area(opt_tasks * CACHELINE_SIZE);
	for (i = 0; i < opt_tasks; i++)
		results[i] = (unsigned long long *)&m[i * CACHELINE_SIZE];

	testcase_prepare();

	hwloc_topology_init(&topology);
	hwloc_topology_load(topology);

	n = hwloc_get_nbobjs_by_type(topology, HWLOC_OBJ_CORE);
	for (i = 0; i < opt_tasks; i++) {
		hwloc_obj_t obj;
		cpu_set_t mask;

		obj = hwloc_get_obj_by_type(topology, HWLOC_OBJ_CORE, i % n);
		hwloc_cpuset_to_glibc_sched_affinity(topology,
				obj->cpuset, &mask, sizeof(mask));
		new_task_affinity(testcase, results[i], sizeof(mask), &mask);
	}

	hwloc_topology_destroy(topology);

	printf("testcase:%s\n", testcase_description);

	printf("warmup\n");

	while (1) {
		unsigned long long sum = 0, min = -1ULL, max = 0;

		sleep(1);

		for (i = 0; i < opt_tasks; i++) {
			unsigned long long val = *(results[i]);
			unsigned long long diff = val - prev[i];

			if (diff < min)
				min = diff;

			if (diff > max)
				max = diff;

			sum += diff;
			prev[i] = val;
		}

		printf("min:%llu max:%llu total:%llu\n", min, max, sum);

		if (iterations == WARMUP_ITERATIONS)
			printf("measurement\n");

		if (iterations++ > WARMUP_ITERATIONS)
			total += sum;

		if (opt_iterations &&
		    (iterations > (opt_iterations + WARMUP_ITERATIONS))) {
			printf("average:%llu\n", total / opt_iterations);
			testcase_cleanup();
			kill_tasks();
			exit(0);
		}
	}
}