How to check currently using semaphores in Solaris ?

Many system administrators, particularly those managing large database servers, have had difficulty tuning shared memory and semaphore parameters in /etc/system. Often, these difficulties are experienced before starting an application instance. The Solaris[TM] 10 Operating System addresses this issue by integrating the System V IPC tunables into a powerful and flexible framework for easy administration. 

If you want to know, how many semaphores  are using on the Solaris system,use below command to check it.

#ipcs -s
IPC status from  as of Thu Jul 26 13:32:36 EDT 2012
T         ID      KEY        MODE        OWNER  GROUP
Semaphores:
s   83886476   0x56bd14   --ra-ra-ra-   test    sap
s  100663690   0x6f471c   --ra-ra-ra-   gnmsf   sap
s  100663689   0x6f3970   --ra-ra-ra-   tm052   sap 
s  100663688   0x6f3330   --ra-ra-ra-   xcdfm   sap 
s   83886977   0x3bfade   --ra-r-----   tm051   sap 
s   83886976   0x3c4900   --ra-r-----   tm051   sap 
s   83886932   0x2dca0e   --ra-r-----   tm056   sap 
s   83886931   0x2e182e   --ra-r-----   tm056   sap
s   83886930   0x2dca0f   --ra-r-----   tm056   sap 
s   83886917   0x33bd7f   --ra-r-----   tm056   sap 
s   67109695   0x2e182f   --ra-r-----   tm056   sap 
s  100664108   0xa173b01a --ra-------    root  root 

You can simple use ipcs -a |wc -l to see the total count.

# ipcs -a |wc -l
15

you have to subtract first three lines from that out. 15-3=12.

#ipcs -sb
IPC status from  as of Thu Jul 26 13:32:36 EDT 2012
T         ID      KEY        MODE        OWNER    GROUP NSEMS
Semaphores:
s   83886476   0x56bd14   --ra-ra-ra-   test    sap     1
s  100663690   0x6f471c   --ra-ra-ra-   gnmsf   sap     1
s  100663689   0x6f3970   --ra-ra-ra-   tm052   sap     1
s  100663688   0x6f3330   --ra-ra-ra-   xcdfm   sap     1
s   83886977   0x3bfade   --ra-r-----   tm051   sap    20
s   83886976   0x3c4900   --ra-r-----   tm051   sap    20
s   83886932   0x2dca0e   --ra-r-----   tm056   sap    20
s   83886931   0x2e182e   --ra-r-----   tm056   sap    20
s   83886930   0x2dca0f   --ra-r-----   tm056   sap    20
s   83886917   0x33bd7f   --ra-r-----   tm056   sap    20
s   67109695   0x2e182f   --ra-r-----   tm056   sap    20
s  100664108   0xa173b01a --ra-------     root  root    1

# id -p
uid=0(root) gid=0(root) projid=1(user.root)
Current project is user.root . you can find the same in /etc/project file as well.
[ QA - Root:~ # ] cat /etc/project
system:0::::
user.root:1::::

To check the maximum system value for above mentioned project user.root,

# prctl -n process.max-sem-nsems $$
process: 26108: bash
NAME    PRIVILEGE       VALUE    FLAG   ACTION                       RECIPIENT
process.max-sem-nsems
        privileged        512       -   deny                                 
        system          32.8K     max   deny                                 
#

Current limit for root user is 512 semaphores .
System Limit is 32.8K

We can modify the values using prctl on the fly.Please refer Resource-management for more information


Thank you for reading this article.Please leave a comment if you have any doubt ,i will get back to you as soon as possible.