Function zone_timeout

freebsd/vm/uma_core.c:976–1032

* Routine to perform timeout driven calculations. This expands the * hashes and does per cpu statistics aggregation. * * Returns nothing. */

 *  Returns nothing.
 */
static void
zone_timeout(uma_zone_t zone, void *unused)
{
	uma_keg_t keg;
	u_int slabs, pages;

	if ((zone->uz_flags & UMA_ZFLAG_HASH) == 0)
		goto update_wss;

	keg = zone->uz_keg;

	/*
	 * Hash zones are non-numa by definition so the first domain
	 * is the only one present.
	 */
	KEG_LOCK(keg, 0);
	pages = keg->uk_domain[0].ud_pages;

	/*
	 * Expand the keg hash table.
	 *
	 * This is done if the number of slabs is larger than the hash size.
	 * What I'm trying to do here is completely reduce collisions.  This
	 * may be a little aggressive.  Should I allow for two collisions max?
	 */
	if ((slabs = pages / keg->uk_ppera) > keg->uk_hash.uh_hashsize) {
		struct uma_hash newhash;
		struct uma_hash oldhash;
		int ret;

		/*
		 * This is so involved because allocating and freeing
		 * while the keg lock is held will lead to deadlock.
		 * I have to do everything in stages and check for
		 * races.
		 */
		KEG_UNLOCK(keg, 0);
		ret = hash_alloc(&newhash, 1 << fls(slabs));
		KEG_LOCK(keg, 0);
		if (ret) {
			if (hash_expand(&keg->uk_hash, &newhash)) {
				oldhash = keg->uk_hash;
				keg->uk_hash = newhash;
			} else
				oldhash = newhash;

			KEG_UNLOCK(keg, 0);
			hash_free(&oldhash);
			goto update_wss;
		}
	}
	KEG_UNLOCK(keg, 0);

update_wss:
	for (int i = 0; i < vm_ndomains; i++)
		zone_domain_update_wss(ZDOM_GET(zone, i));
}