VMS Help V73 Features, System Management Features, Dedicated CPU Lock Manager (Alpha), Implementing  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    For the Dedicated CPU Lock Manager to be effective, systems
    must have a high CPU count and a high amount of MP_SYNCH due
    to the lock manager. Use the MONITOR utility and the MONITOR
    MODE command to see the amount of MP_SYNCH. If your system has
    more than five CPUs and if MP_SYNCH is higher than 200%, your
    system may be able to take advantage of the Dedicated CPU Lock
    Manager. You can also use the spinlock trace feature in the
    System Dump Analyzer (SDA) to help determine if the lock manager
    is contributing to the high amount of MP_SYNCH time.

    The Dedicated CPU Lock Manager is implemented by a LCKMGR_SERVER
    process. This process runs at priority 63. When the Dedicated
    CPU Lock Manager is turned on, this process runs in a compute
    bound loop looking for lock manager work to perform. Because
    this process polls for work, it is always computable; and with
    a priority of 63 the process will never give up the CPU, thus
    consuming a whole CPU.

    If the Dedicated CPU Lock Manager is running when a program calls
    either the $ENQ or $DEQ system services, a lock manager request
    is placed on a work queue for the Dedicated CPU Lock Manager.
    While a process waits for a lock request to be processed, the
    process spins in kernel mode at IPL 2. After the dedicated CPU
    processes the request, the status for the system service is
    returned to the process.

    The Dedicated CPU Lock Manager is dynamic and can be turned off
    if there are no perceived benefits. When the Dedicated CPU Lock
    Manager is turned off, the LCKMGR_SERVER process is in a HIB
    (hibernate) state. The process may not be deleted once started.