Function keg_drain_domain

freebsd/vm/uma_core.c:1399–1454

}

static void
keg_drain_domain(uma_keg_t keg, int domain)
{
	struct slabhead freeslabs;
	uma_domain_t dom;
	uma_slab_t slab, tmp;
	uint32_t i, stofree, stokeep, partial;

	dom = &keg->uk_domain[domain];
	LIST_INIT(&freeslabs);

	CTR4(KTR_UMA, "keg_drain %s(%p) domain %d free items: %u",
	    keg->uk_name, keg, domain, dom->ud_free_items);

	KEG_LOCK(keg, domain);

	/*
	 * Are the free items in partially allocated slabs sufficient to meet
	 * the reserve? If not, compute the number of fully free slabs that must
	 * be kept.
	 */
	partial = dom->ud_free_items - dom->ud_free_slabs * keg->uk_ipers;
	if (partial < keg->uk_reserve) {
		stokeep = min(dom->ud_free_slabs,
		    howmany(keg->uk_reserve - partial, keg->uk_ipers));
	} else {
		stokeep = 0;
	}
	stofree = dom->ud_free_slabs - stokeep;

	/*
	 * Partition the free slabs into two sets: those that must be kept in
	 * order to maintain the reserve, and those that may be released back to
	 * the system.  Since one set may be much larger than the other,
	 * populate the smaller of the two sets and swap them if necessary.
	 */
	for (i = min(stofree, stokeep); i > 0; i--) {
		slab = LIST_FIRST(&dom->ud_free_slab);
		LIST_REMOVE(slab, us_link);
		LIST_INSERT_HEAD(&freeslabs, slab, us_link);
	}
	if (stofree > stokeep)
		LIST_SWAP(&freeslabs, &dom->ud_free_slab, uma_slab, us_link);

	if ((keg->uk_flags & UMA_ZFLAG_HASH) != 0) {
		LIST_FOREACH(slab, &freeslabs, us_link)
			UMA_HASH_REMOVE(&keg->uk_hash, slab);
	}
	dom->ud_free_items -= stofree * keg->uk_ipers;
	dom->ud_free_slabs -= stofree;
	dom->ud_pages -= stofree * keg->uk_ppera;
	KEG_UNLOCK(keg, domain);

	LIST_FOREACH_SAFE(slab, &freeslabs, us_link, tmp)
		keg_free_slab(keg, slab, keg->uk_ipers);
}

/*