Technical data

System Dump Analyzer
SHOW SPINLOCKS
/STATIC
Displays information for all system spin locks and fork locks.
Description
The SHOW SPINLOCKS command displays status and diagnostic information
about the multiprocessing synchronization structures known as spin locks.
A static spin lock is a spin lock whose data structure is permanently assembled
into the system. Static spin locks are accessed as indexes into a vector of
longword addresses called the spin lock vector, the address of which is
contained in SMP$AR_SPNLKVEC. System spin locks and fork locks are static
spin locks. Table SDA–22 lists the static spin locks.
A dynamic spin lock is a spin lock that is created based on the configuration
of a particular system. One such dynamic spin lock is the device lock SYSGEN
creates when configuring a particular device. This device lock synchronizes
access to the device’s registers and certain UCB fields. The operating system
creates a dynamic spin lock by allocating space from nonpaged pool, rather than
assembling the lock into the system as it does in creating a static spin lock.
See the OpenVMS VAX Device Support Manual
15
for a full discussion of the
role of spin locks in maintaining synchronization of kernel mode activities in a
multiprocessing environment.
Table SDA–22 Static Spin Locks
Name Description
QUEUEAST Fork lock for queuing ASTs at IPL 6
FILSYS Lock on file system structures
IOLOCK8 Fork lock for executing a driver fork process at IPL 8
PR_LK8 Primary CPU’s private lock for IPL 8
TIMER Lock for adding and deleting timer queue entries and searching the timer
queue
JIB Lock for manipulating job nonpaged pool quotas as reflected by the fields
JIB$L_BYTCNT and JIB$L_BYTLM in the job information block (JIB)
MMG Lock on memory management, PFN database, swapper, modified page
writer, and creation of per-CPU database structures
SCHED Lock on process control blocks (PCBs), scheduler database, and mutex
acquisition and release structures
IOLOCK9 Fork lock for executing a driver fork process at IPL 9
PR_LK9 Primary CPU’s private lock for IPL 9
IOLOCK10 Fork lock for executing a driver fork process at IPL 10
PR_LK10 Primary CPU’s private lock for IPL 10
IOLOCK11 Fork lock for executing a driver fork process at IPL 11
PR_LK11 Primary CPU’s private lock for IPL 11
(continued on next page)
15
This manual has been archived but is available on the OpenVMS Documentation
CD-ROM.
SDA–170