Function vm_pageout_worker

freebsd/vm/vm_pageout.c:2085–2171

}

static void
vm_pageout_worker(void *arg)
{
	struct vm_domain *vmd;
	u_int ofree;
	int addl_shortage, domain, shortage;
	bool target_met;

	domain = (uintptr_t)arg;
	vmd = VM_DOMAIN(domain);
	shortage = 0;
	target_met = true;

	/*
	 * XXXKIB It could be useful to bind pageout daemon threads to
	 * the cores belonging to the domain, from which vm_page_array
	 * is allocated.
	 */

	KASSERT(vmd->vmd_segs != 0, ("domain without segments"));
	vmd->vmd_last_active_scan = ticks;

	/*
	 * The pageout daemon worker is never done, so loop forever.
	 */
	while (TRUE) {
		vm_domain_pageout_lock(vmd);

		/*
		 * We need to clear wanted before we check the limits.  This
		 * prevents races with wakers who will check wanted after they
		 * reach the limit.
		 */
		atomic_store_int(&vmd->vmd_pageout_wanted, 0);

		/*
		 * Might the page daemon need to run again?
		 */
		if (vm_paging_needed(vmd, vmd->vmd_free_count)) {
			/*
			 * Yes.  If the scan failed to produce enough free
			 * pages, sleep uninterruptibly for some time in the
			 * hope that the laundry thread will clean some pages.
			 */
			vm_domain_pageout_unlock(vmd);
			if (!target_met)
				pause("pwait", hz / VM_INACT_SCAN_RATE);
		} else {
			/*
			 * No, sleep until the next wakeup or until pages
			 * need to have their reference stats updated.
			 */
			if (mtx_sleep(&vmd->vmd_pageout_wanted,
			    vm_domain_pageout_lockptr(vmd), PDROP | PVM,
			    "psleep", hz / VM_INACT_SCAN_RATE) == 0)
				VM_CNT_INC(v_pdwakeups);
		}