--- /dev/null
+/*
+ * Context switch microbenchmark.
+ *
+ * Copyright (C) 2015 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 <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <signal.h>
+#include <assert.h>
+#include <pthread.h>
+#include <limits.h>
+#include <sys/time.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/shm.h>
+#include <linux/futex.h>
+
+static unsigned int timeout = INT_MAX;
+
+static int touch_vdso;
+struct timeval tv;
+
+static int touch_fp;
+double fp;
+
+static int touch_vector;
+typedef int v4si __attribute__ ((vector_size (16)));
+v4si a, b, c;
+
+#ifdef __powerpc__
+static int touch_altivec;
+
+static void __attribute__((__target__("no-vsx"))) altivec_touch_fn(void)
+{
+ c = a + b;
+}
+#endif
+
+static void touch(void)
+{
+ if (touch_vdso)
+ gettimeofday(&tv, NULL);
+
+ if (touch_fp)
+ fp += 0.1;
+
+#ifdef __powerpc__
+ if (touch_altivec)
+ altivec_touch_fn();
+#endif
+
+ if (touch_vector)
+ c = a + b;
+
+ asm volatile("# %0 %1 %2": : "r"(&tv), "r"(&fp), "r"(&c));
+}
+
+static void start_thread_on(void *(*fn)(void *), void *arg, unsigned long cpu)
+{
+ pthread_t tid;
+ cpu_set_t cpuset;
+ pthread_attr_t attr;
+
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu, &cpuset);
+
+ pthread_attr_init(&attr);
+
+ if (pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset)) {
+ perror("pthread_attr_setaffinity_np");
+ exit(1);
+ }
+
+ if (pthread_create(&tid, &attr, fn, arg)) {
+ perror("pthread_create");
+ exit(1);
+ }
+}
+
+static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu)
+{
+ int pid;
+ cpu_set_t cpuset;
+
+ pid = fork();
+ if (pid == -1) {
+ perror("fork");
+ exit(1);
+ }
+
+ if (pid)
+ return;
+
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu, &cpuset);
+
+ if (sched_setaffinity(0, sizeof(cpuset), &cpuset)) {
+ perror("sched_setaffinity");
+ exit(1);
+ }
+
+ fn(arg);
+
+ exit(0);
+}
+
+static unsigned long iterations;
+static unsigned long iterations_prev;
+
+static void sigalrm_handler(int junk)
+{
+ unsigned long i = iterations;
+
+ printf("%ld\n", i - iterations_prev);
+ iterations_prev = i;
+
+ if (--timeout == 0)
+ kill(0, SIGUSR1);
+
+ alarm(1);
+}
+
+static void sigusr1_handler(int junk)
+{
+ exit(0);
+}
+
+struct actions {
+ void (*setup)(int, int);
+ void *(*thread1)(void *);
+ void *(*thread2)(void *);
+};
+
+#define READ 0
+#define WRITE 1
+
+static int pipe_fd1[2];
+static int pipe_fd2[2];
+
+static void pipe_setup(int cpu1, int cpu2)
+{
+ if (pipe(pipe_fd1) || pipe(pipe_fd2))
+ exit(1);
+}
+
+static void *pipe_thread1(void *arg)
+{
+ signal(SIGALRM, sigalrm_handler);
+ alarm(1);
+
+ while (1) {
+ assert(read(pipe_fd1[READ], &c, 1) == 1);
+ touch();
+
+ assert(write(pipe_fd2[WRITE], &c, 1) == 1);
+ touch();
+
+ iterations += 2;
+ }
+
+ return NULL;
+}
+
+static void *pipe_thread2(void *arg)
+{
+ while (1) {
+ assert(write(pipe_fd1[WRITE], &c, 1) == 1);
+ touch();
+
+ assert(read(pipe_fd2[READ], &c, 1) == 1);
+ touch();
+ }
+
+ return NULL;
+}
+
+static struct actions pipe_actions = {
+ .setup = pipe_setup,
+ .thread1 = pipe_thread1,
+ .thread2 = pipe_thread2,
+};
+
+static void yield_setup(int cpu1, int cpu2)
+{
+ if (cpu1 != cpu2) {
+ fprintf(stderr, "Both threads must be on the same CPU for yield test\n");
+ exit(1);
+ }
+}
+
+static void *yield_thread1(void *arg)
+{
+ signal(SIGALRM, sigalrm_handler);
+ alarm(1);
+
+ while (1) {
+ sched_yield();
+ touch();
+
+ iterations += 2;
+ }
+
+ return NULL;
+}
+
+static void *yield_thread2(void *arg)
+{
+ while (1) {
+ sched_yield();
+ touch();
+ }
+
+ return NULL;
+}
+
+static struct actions yield_actions = {
+ .setup = yield_setup,
+ .thread1 = yield_thread1,
+ .thread2 = yield_thread2,
+};
+
+static long sys_futex(void *addr1, int op, int val1, struct timespec *timeout,
+ void *addr2, int val3)
+{
+ return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
+}
+
+static unsigned long cmpxchg(unsigned long *p, unsigned long expected,
+ unsigned long desired)
+{
+ unsigned long exp = expected;
+
+ __atomic_compare_exchange_n(p, &exp, desired, 0,
+ __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+ return exp;
+}
+
+static unsigned long xchg(unsigned long *p, unsigned long val)
+{
+ return __atomic_exchange_n(p, val, __ATOMIC_SEQ_CST);
+}
+
+static int mutex_lock(unsigned long *m)
+{
+ int c;
+
+ c = cmpxchg(m, 0, 1);
+ if (!c)
+ return 0;
+
+ if (c == 1)
+ c = xchg(m, 2);
+
+ while (c) {
+ sys_futex(m, FUTEX_WAIT, 2, NULL, NULL, 0);
+ c = xchg(m, 2);
+ }
+
+ return 0;
+}
+
+static int mutex_unlock(unsigned long *m)
+{
+ if (*m == 2)
+ *m = 0;
+ else if (xchg(m, 0) == 1)
+ return 0;
+
+ sys_futex(m, FUTEX_WAKE, 1, NULL, NULL, 0);
+
+ return 0;
+}
+
+static unsigned long *m1, *m2;
+
+static void futex_setup(int cpu1, int cpu2)
+{
+ int shmid;
+ void *shmaddr;
+
+ shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
+ if (shmid < 0) {
+ perror("shmget");
+ exit(1);
+ }
+
+ shmaddr = shmat(shmid, NULL, 0);
+ if (shmaddr == (char *)-1) {
+ perror("shmat");
+ shmctl(shmid, IPC_RMID, NULL);
+ exit(1);
+ }
+
+ shmctl(shmid, IPC_RMID, NULL);
+
+ m1 = shmaddr;
+ m2 = shmaddr + sizeof(*m1);
+
+ *m1 = 0;
+ *m2 = 0;
+
+ mutex_lock(m1);
+ mutex_lock(m2);
+}
+
+static void *futex_thread1(void *arg)
+{
+ signal(SIGALRM, sigalrm_handler);
+ alarm(1);
+
+ while (1) {
+ mutex_lock(m2);
+ mutex_unlock(m1);
+
+ iterations += 2;
+ }
+
+ return NULL;
+}
+
+static void *futex_thread2(void *arg)
+{
+ while (1) {
+ mutex_unlock(m2);
+ mutex_lock(m1);
+ }
+
+ return NULL;
+}
+
+static struct actions futex_actions = {
+ .setup = futex_setup,
+ .thread1 = futex_thread1,
+ .thread2 = futex_thread2,
+};
+
+static int processes;
+
+static struct option options[] = {
+ { "test", required_argument, 0, 't' },
+ { "process", no_argument, &processes, 1 },
+ { "timeout", required_argument, 0, 's' },
+ { "vdso", no_argument, &touch_vdso, 1 },
+ { "fp", no_argument, &touch_fp, 1 },
+#ifdef __powerpc__
+ { "altivec", no_argument, &touch_altivec, 1 },
+#endif
+ { "vector", no_argument, &touch_vector, 1 },
+ { 0, },
+};
+
+static void usage(void)
+{
+ fprintf(stderr, "Usage: context_switch2 <options> CPU1 CPU2\n\n");
+ fprintf(stderr, "\t\t--test=X\tpipe, futex or yield\n");
+ fprintf(stderr, "\t\t--process\tUse processes (default threads)\n");
+ fprintf(stderr, "\t\t--timeout=X\tDuration in seconds to run\n");
+ fprintf(stderr, "\t\t--vdso\t\ttouch VDSO\n");
+ fprintf(stderr, "\t\t--fp\t\ttouch FP\n");
+#ifdef __powerpc__
+ fprintf(stderr, "\t\t--altivec\ttouch altivec\n");
+#endif
+ fprintf(stderr, "\t\t--vector\ttouch vector\n");
+}
+
+int main(int argc, char *argv[])
+{
+ signed char c;
+ struct actions *actions = &pipe_actions;
+ int cpu1;
+ int cpu2;
+ static void (*start_fn)(void *(*fn)(void *), void *arg, unsigned long cpu);
+
+ while (1) {
+ int option_index = 0;
+
+ c = getopt_long(argc, argv, "", options, &option_index);
+
+ if (c == -1)
+ break;
+
+ switch (c) {
+ case 0:
+ if (options[option_index].flag != 0)
+ break;
+
+ usage();
+ exit(1);
+ break;
+
+ case 't':
+ if (!strcmp(optarg, "pipe")) {
+ actions = &pipe_actions;
+ } else if (!strcmp(optarg, "yield")) {
+ actions = &yield_actions;
+ } else if (!strcmp(optarg, "futex")) {
+ actions = &futex_actions;
+ } else {
+ usage();
+ exit(1);
+ }
+ break;
+
+ case 's':
+ timeout = atoi(optarg);
+ break;
+
+ default:
+ usage();
+ exit(1);
+ }
+ }
+
+ if (processes)
+ start_fn = start_process_on;
+ else
+ start_fn = start_thread_on;
+
+ if (((argc - optind) != 2)) {
+ usage();
+ exit(1);
+ }
+
+ /* Create a new process group so we can signal everyone for exit */
+ setpgid(getpid(), getpid());
+
+ signal(SIGUSR1, sigusr1_handler);
+
+ cpu1 = atoi(argv[optind++]);
+ cpu2 = atoi(argv[optind++]);
+
+ actions->setup(cpu1, cpu2);
+
+ start_fn(actions->thread1, NULL, cpu1);
+ start_fn(actions->thread2, NULL, cpu2);
+
+ while (1)
+ sleep(3600);
+
+ return 0;
+}
projects / cascardo / linux.git / commitdiff