Function threadinit

freebsd/kern/kern_thread.c:486–545

* Initialize global thread allocation resources. */

 * Initialize global thread allocation resources.
 */
void
threadinit(void)
{
	u_long i;
	lwpid_t tid0;
	uint32_t flags;

	/*
	 * Place an upper limit on threads which can be allocated.
	 *
	 * Note that other factors may make the de facto limit much lower.
	 *
	 * Platform limits are somewhat arbitrary but deemed "more than good
	 * enough" for the foreseable future.
	 */
	if (maxthread == 0) {
#ifdef _LP64
		maxthread = MIN(maxproc * max_threads_per_proc, 1000000);
#else
		maxthread = MIN(maxproc * max_threads_per_proc, 100000);
#endif
	}

	mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
	tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK);
	/*
	 * Handle thread0.
	 */
	thread_count_inc();
	tid0 = tid_alloc();
	if (tid0 != THREAD0_TID)
		panic("tid0 %d != %d\n", tid0, THREAD0_TID);

	flags = UMA_ZONE_NOFREE;
#ifdef __aarch64__
	/*
	 * Force thread structures to be allocated from the direct map.
	 * Otherwise, superpage promotions and demotions may temporarily
	 * invalidate thread structure mappings.  For most dynamically allocated
	 * structures this is not a problem, but translation faults cannot be
	 * handled without accessing curthread.
	 */
	flags |= UMA_ZONE_CONTIG;
#endif
	thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
	    thread_ctor, thread_dtor, thread_init, thread_fini,
	    32 - 1, flags);
	tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
	tidhashlock = (tidhash + 1) / 64;
	if (tidhashlock > 0)
		tidhashlock--;
	tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1),
	    M_TIDHASH, M_WAITOK | M_ZERO);
	for (i = 0; i < tidhashlock + 1; i++)
		rw_init(&tidhashtbl_lock[i], "tidhash");

	TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL);
	callout_init(&thread_reap_callout, 1);