Technical data

System Management Features
4.4 Dedicated CPU Lock Manager (Alpha)
In addition, if the number of active CPUs should ever be reduced below the
required threshold by either a STOP/CPU command or by CPU reassignment in
a Galaxy configuration, the Dedicated CPU Lock Manager automatically turns
off within one second, and the LCKMGR_SERVER process goes into a hibernate
state. If the CPU is restarted, the LCKMGR_SERVER process again resumes
operations.
4.4.3 Using the Dedicated CPU Lock Manager With Affinity
The LCKMGR_SERVER process uses the affinity mechanism to set the process
to the lowest CPU ID other than the primary. You can change this by indicating
another CPU ID with the LCKMGR_CPUID system parameter. The Dedicated
CPU Lock Manager then attempts to use this CPU. If this CPU is not available,
it reverts back to the lowest CPU other than the primary.
The following shows how to dynamically change the CPU used by the LCKMGR_
SERVER process:
$RUN SYS$SYSTEM:SYSGEN
SYSGEN>USE ACTIVE
SYSGEN>SET LCKMGR_CPUID 2
SYSGEN>WRITE ACTIVE
SYSGEN>EXIT
This change applies to the currently running system. A reboot reverts back to the
lowest CPU other than the primary. To permanently change the CPU used by the
LCKMGR_SERVER process, set LCKMGR_CPUID in your MODPARAMS.DAT
file.
To verify the CPU dedicated to the lock manager, use the SHOW SYSTEM
command, as follows:
$ SHOW SYSTEM/PROCESS=LCKMGR_SERVER
OpenVMS V7.3 on node JYGAL 24-OCT-2000 10:10:11.31 Uptime 3 20:16:56
Pid Process Name State Pri I/O CPU Page flts Pages
4CE0021C LCKMGR_SERVER CUR 2 63 9 3 20:15:47.78 70 84
Note that the State field shows the process is currently running on CPU 2.
Compaq highly recommends that a process not be given hard affinity to the
CPU used by the Dedicated CPU Lock Manager. With hard affinity when such
a process becomes computable, it cannot obtain any CPU time, because the
LCKMGR_SERVER process is running at the highest possible real-time priority
of 63. However, the LCKMGR_SERVER detects once per second if there are any
computable processes that are set by the affinity mechanism to the dedicated lock
manager CPU. If so, the LCKMGR_SERVER switches to a different CPU for one
second to allow the waiting process to run.
4.4.4 Using the Dedicated CPU Lock Manager with Fast Path Devices
OpenVMS Version 7.3 also introduces Fast Path for SCSI and Fibre Channel
Controllers along with the existing support of CIPCA adapters. The Dedicated
CPU Lock Manager supports both the LCKMGR_SERVER process and Fast Path
devices on the same CPU. However, this may not produce optimal performance.
By default, the LCKMGR_SERVER process runs on the first available nonprimary
CPU. Compaq recommends that the CPU used by the LCKMGR_SERVER process
not have any Fast Path devices. This can be accomplished in either of the
following ways:
System Management Features 4–5