Technical data

System Management Release Notes
5.7 Lock Manager
5.7.2 Instituting the Dedicated CPU Lock Manager Functionality (Alpha Only)
V7.3
With OpenVMS Version 7.3, Compaq introduces an alternative locking mode
that allows a CPU to be dedicated to the lock manager. The dedicated CPU
lock manager can perform better than the traditional lock manager under heavy
locking loads. The performance gains are a result of reducing SMP contention
and obtaining the benefits of improved CPU cache utilization on the CPU
dedicated to the lock manager.
Usage of the dedicated CPU lock manager is only of benefit to systems with a
large number of CPUs and heavy SMP contention due to the lock manager. By
default, a CPU will not be dedicated to the lock manager. See the OpenVMS
Version 7.3 New Features and Documentation Overview for information and
details about enabling the dedicated CPU lock manager.
5.7.3 Fast Lock Remastering and PE1 (Alpha Only)
V7.3
The OpenVMS Distributed Lock Manager has a feature called lock remastering.
A lock remaster is the process of moving the lock mastership of a resource tree to
another node in the cluster. The node that masters a lock tree can process local
locking requests much faster because communication is not required with another
node in the cluster. Having a lock tree reside on the node doing the most locking
operations can improve overall system performance.
Prior to OpenVMS Version 7.3, lock remastering resulted in all nodes sending
one message per local lock to the new master. For a very large lock tree, it could
require a substantial amount of time to perform the lock remastering operation.
During the operation, all application locking to the lock tree is stalled.
Starting with OpenVMS Version 7.3, sending lock data to the new master is done
with very large transfers. This is a much more efficient process and results in
moving a lock tree from 3 to 20 times faster.
Only nodes running Version 7.3 or later can use large transfers for lock
remastering. Remastering between OpenVMS Version 7.3 nodes and prior
version nodes still requires sending a single message per lock.
If you currently use the PE1 system parameter to limit the size of lock trees that
can be remastered, Compaq recommends that you either try increasing the value
to allow large lock trees to move or try setting the value to zero (0) to allow any
size lock tree to move.
5.7.4 Lock Manager and Nonpaged Pool (Alpha Only)
V7.2
To improve application scalability on OpenVMS Alpha systems, most of the lock
manager data structures have been moved from nonpaged pool to S2 space. On
many systems, the lock manager data structures accounted for a large percentage
of nonpaged pool usage.
5–10 System Management Release Notes