number of semaphores and semaphore sets

This page:
http://www.postgresql.org/docs/9.0/interactive/kernel-resources.html

has formula:
ceil((max_connections + autovacuum_max_workers) / 16)

for number of semaphore sets (identifiers).

It seems to be wrong (outdated).

Correct formula seems to be

ceil((max_connections + autovacuum_max_workers + 4) / 16)

Semaphore sets created in src/backend/storage/lmgr/proc.c:
1. MaxConnections
2. autovacuum_max_workers + 1
3. NUM_AUXILIARY_PROCS (currently 3)

--
  Anton Yuzhaninov