Kbase 18742: How to see the activity of semaphores in a unix platform.
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
3/18/2003 |
|
How to see the activity of semaphores in a UNIX platform.
The follow utility can be used to state the semaphore activity.
sar -m
Report interprocess communication (IPC) message queue and semaphore
activity:
If you are not running application programs that use message queues
and semaphores sar display: 0.00. If you use this and the value of
sema/s is high and you have a performance problem or 290 error, etc,
the application may not be using IPC efficiently.
server$ sar -m 2 5
where 2 is the interval in seconds and 5 the number of times that sar
information is displayed
04:15:57 msg/s sema/s
04:15:59 0.00 113.50
04:16:01 0.00 104.00
04:16:03 0.00 71.78
04:16:05 0.00 64.36
04:16:07 0.00 58.29
Average 0.00 82.35
IPC (Inter-Process Communication) Parameters:
SHMMNI:
The maximum number of shared memory identifiers allowed for the system
SHMALL:
The maximum number of in-use shared memory segments allowed for the
system. Some systems do not have this parameter.
(for example, Sun OS, DG 5.4, SCO UNIX 5.0.5 increases this value dynamically).
SHMMAX:
The maximum size of a single shared memory segment. Some systems
call this parameter SHMSIZE (for example, Sun OS).
SHMSEG:
The maximum number of shared memory segments a single process.
(SCO UNIX 5.0.5 increases this value dynamically)
SEMMNI:
The maximum number of semaphore identifiers allowed for the system.
SEMMSL:
The maximum number of semaphores allowed per semaphore identifier
(semaphore set).
SEMMNS: (some SV4 systems may dynamically allocate this parameter)
Total number of semaphores allowed for the system.
SEMMNU: (some SV4 systems name this paramter SEMUME (eg DG)
Maximum number of semaphore undo structures allowed for the system.
For more information see Kbase 18621
Number of semaphores:
The Progress broker preallocates semaphores when you start the DB
with PROSERVE. Each process requires one semaphore. Progress uses
two additional semaphores internally. Progress uses the following
formula to determine the number of semaphores (#SEM) to allocate.
#SEM = Max-possible-users (-n) + Max-possible-servers (-Mn) + 4
For more information, see the System Administration Guide --
"Managing Progress Performance"