This option controls the number of worker processes that are started for each service when prefork process model is enabled (see samba 8 -M) The prefork children are only started for those services that support prefork (currently ldap, kdc and netlogon). For processes that don't support preforking all requests are handled by a single process for that service.
This should be set to a small multiple of the number of CPU's available on the server
Additionally the number of prefork children can be specified for an individual service by using "prefork children: service name" i.e. "prefork children:ldap = 8" to set the number of ldap worker processes.
|Registry Path||Software\Policies\Samba\smb_conf\prefork children|
|Value Name||prefork children|