Function vm_pageout_scan_inactive

freebsd/vm/vm_pageout.c:1425–1648

}

static void
vm_pageout_scan_inactive(struct vm_domain *vmd, int page_shortage)
{
	struct timeval start, end;
	struct scan_state ss;
	struct vm_batchqueue rq;
	struct vm_page marker_page;
	vm_page_t m, marker;
	struct vm_pagequeue *pq;
	vm_object_t object;
	vm_page_astate_t old, new;
	int act_delta, addl_page_shortage, starting_page_shortage, refs;

	object = NULL;
	vm_batchqueue_init(&rq);
	getmicrouptime(&start);

	/*
	 * The addl_page_shortage is an estimate of the number of temporarily
	 * stuck pages in the inactive queue.  In other words, the
	 * number of pages from the inactive count that should be
	 * discounted in setting the target for the active queue scan.
	 */
	addl_page_shortage = 0;

	/*
	 * Start scanning the inactive queue for pages that we can free.  The
	 * scan will stop when we reach the target or we have scanned the
	 * entire queue.  (Note that m->a.act_count is not used to make
	 * decisions for the inactive queue, only for the active queue.)
	 */
	starting_page_shortage = page_shortage;
	marker = &marker_page;
	vm_page_init_marker(marker, PQ_INACTIVE, 0);
	pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
	vm_pagequeue_lock(pq);
	vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt);
	while (page_shortage > 0 && (m = vm_pageout_next(&ss, true)) != NULL) {
		KASSERT((m->flags & PG_MARKER) == 0,
		    ("marker page %p was dequeued", m));

		/*
		 * Don't touch a page that was removed from the queue after the
		 * page queue lock was released.  Otherwise, ensure that any
		 * pending queue operations, such as dequeues for wired pages,
		 * are handled.
		 */
		if (vm_pageout_defer(m, PQ_INACTIVE, false))
			continue;

		/*
		 * Lock the page's object.
		 */
		if (object == NULL || object != m->object) {
			if (object != NULL)
				VM_OBJECT_WUNLOCK(object);
			object = atomic_load_ptr(&m->object);
			if (__predict_false(object == NULL))