cpu register interface

pthread_barrier

userland/linux/sched_getcpu_barrier.c

@@ -0,0 +1,46 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#getcpu */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+pthread_barrier_t barrier;
+
+void* main_thread(void *arg) {
+    (void)arg;
+    printf("%d\n", sched_getcpu());
+    pthread_barrier_wait(&barrier);
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *threads;
+    unsigned int nthreads, i;
+    if (argc > 1) {
+        nthreads = strtoll(argv[1], NULL, 0);
+    } else {
+        nthreads = 1;
+    }
+    assert(!pthread_barrier_init(&barrier, NULL, nthreads));
+    threads = malloc(nthreads * sizeof(*threads));
+    for (i = 0; i < nthreads; ++i) {
+        assert(pthread_create(
+            &threads[i],
+            NULL,
+            main_thread,
+            NULL
+        ) == 0);
+    }
+    for (i = 0; i < nthreads; ++i) {
+        pthread_join(threads[i], NULL);
+    }
+    free(threads);
+    assert(!pthread_barrier_destroy(&barrier));
+    return EXIT_SUCCESS;
+}

userland/posix/pthread_barrier.c

@@ -0,0 +1,47 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#pthreads */
+
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+pthread_barrier_t barrier;
+
+void* main_thread(void *arg) {
+    (void)arg;
+    printf("before %ju\n", (uintmax_t)pthread_self());
+    pthread_barrier_wait(&barrier);
+    printf("after  %ju\n", (uintmax_t)pthread_self());
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *threads;
+    unsigned int nthreads, i;
+    if (argc > 1) {
+        nthreads = strtoll(argv[1], NULL, 0);
+    } else {
+        nthreads = 1;
+    }
+    assert(!pthread_barrier_init(&barrier, NULL, nthreads));
+    threads = malloc(nthreads * sizeof(*threads));
+    for (i = 0; i < nthreads; ++i) {
+        assert(pthread_create(
+            &threads[i],
+            NULL,
+            main_thread,
+            NULL
+        ) == 0);
+    }
+    for (i = 0; i < nthreads; ++i) {
+        pthread_join(threads[i], NULL);
+    }
+    free(threads);
+    assert(!pthread_barrier_destroy(&barrier));
+    return EXIT_SUCCESS;
+}