Version 1.17.1
Configure line: LIBS=-ljemalloc CFLAGS=-g -fno-omit-frame-pointer -flto -O2 --enable-subnet --with-libevent --with-pthreads --with-ssl
Linked libs: libevent 2.1.8-stable (it uses epoll), OpenSSL 1.1.1k  FIPS 25 Mar 2021
Linked modules: dns64 subnetcache respip validator iterator
BSD licensed, see LICENSE in source package for details.
Report bugs to unbound-bugs@nlnetlabs.nl or https://github.com/NLnetLabs/unbound/issues

module-config: "subnetcache iterator"
client-subnet-always-forward: yes
max-client-subnet-ipv6: 56
max-client-subnet-ipv4: 24
min-client-subnet-ipv6: 0
min-client-subnet-ipv4: 0
max-ecs-tree-size-ipv4: 256
max-ecs-tree-size-ipv6: 10

        ......
	for (i = 0; i < elem->rrset_count; i++) {
		struct ub_packed_rrset_key *key = elem->rrsets[i];
		struct packed_rrset_data *data = key->entry.data;
		s += ub_rrset_sizefunc(key, data);
	} 

void
lruhash_update_space_used(struct lruhash* table, hashvalue_type hash,
        struct lruhash_entry* entry, void* data, void* cb_arg, size_t diff_size)
{
	struct lruhash_entry *reclaimlist = NULL;
	(void)hash;
	(void)entry;
	(void)data;
	fptr_ok(fptr_whitelist_hash_sizefunc(table->sizefunc));
	fptr_ok(fptr_whitelist_hash_delkeyfunc(table->delkeyfunc));
	fptr_ok(fptr_whitelist_hash_deldatafunc(table->deldatafunc));
	fptr_ok(fptr_whitelist_hash_compfunc(table->compfunc));
	fptr_ok(fptr_whitelist_hash_markdelfunc(table->markdelfunc));
	if(cb_arg == NULL) cb_arg = table->cb_arg;
	/* find bin */
	lock_quick_lock(&table->lock);
	table->space_used += diff_size;
	if(table->space_used > table->space_max)
		reclaim_space(table, &reclaimlist);
	lock_quick_unlock(&table->lock);
	/* finish reclaim if any (outside of critical region) */
	while(reclaimlist) {
		struct lruhash_entry* n = reclaimlist->overflow_next;
		void* d = reclaimlist->data;
		(*table->delkeyfunc)(reclaimlist->key, cb_arg);
		(*table->deldatafunc)(d, cb_arg);
		reclaimlist = n;
	}
}

        ......
	diff_size = tree->size_bytes;
	addrtree_insert(tree, (addrkey_t*)edns->subnet_addr,
		edns->subnet_source_mask, sq->max_scope, rep,
		rep->ttl, *qstate->env->now, only_match_scope_zero);
	diff_size = tree->size_bytes - diff_size;
	lock_rw_unlock(&lru_entry->lock);
	if (need_to_insert) {
		slabhash_insert(subnet_msg_cache, h, lru_entry, lru_entry->data,
			NULL);
	} else {
		 slabhash_update_space_used(subnet_msg_cache, h, lru_entry, lru_entry->data,
			NULL, diff_size);
	}