1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright 2015, Cyril Bur, IBM Corp.
5 * This test attempts to see if the FPU registers change across preemption.
6 * Two things should be noted here a) The check_fpu function in asm only checks
7 * the non volatile registers as it is reused from the syscall test b) There is
8 * no way to be sure preemption happened so this test just uses many threads
9 * and a long wait. As such, a successful test doesn't mean much but a failure
15 #include <sys/syscall.h>
17 #include <sys/types.h>
24 /* Time to wait for workers to get preempted (seconds) */
25 #define PREEMPT_TIME 20
27 * Factor by which to multiply number of online CPUs for total number of
30 #define THREAD_FACTOR 8
33 __thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
34 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
40 extern int preempt_fpu(double *darray, int *threads_starting, int *running);
42 void *preempt_fpu_c(void *p)
47 srand(pthread_self());
48 for (i = 0; i < 21; i++)
51 rc = preempt_fpu(darray, &threads_starting, &running);
56 int test_preempt_fpu(void)
61 threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
62 tids = malloc((threads) * sizeof(pthread_t));
66 threads_starting = threads;
67 for (i = 0; i < threads; i++) {
68 rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL);
73 /* Not really necessary but nice to wait for every thread to start */
74 printf("\tWaiting for all workers to start...");
75 while(threads_starting)
76 asm volatile("": : :"memory");
79 printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
83 printf("\tStopping workers...");
85 * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'.
86 * r5 will have loaded the value of running.
89 for (i = 0; i < threads; i++) {
91 pthread_join(tids[i], &rc_p);
94 * Harness will say the fail was here, look at why preempt_fpu
107 int main(int argc, char *argv[])
109 return test_harness(test_preempt_fpu, "fpu_preempt");