eG Monitoring
 

Measures reported by IpcsSemaphorTest

Semaphores are data structures that are used for synchronization between two or more processes. . They are often used to monitor and control the availability of system resources such as shared memory segments. Basically, they can be viewed as a single integer that represents the amout of resources available. When a process wants a resource, it checks the value of the semaphore, and if it it non-zero, it decrements the appropriate number from the semaphore in accordance to the amout of resources it wishes to use. The kernel will block the process if the semaphore is zero or doesn't have a value high enough for the decrement.

Semaphores can be operated on as individual units or as elements in a set. A semaphore set consists of a control structure and an array of individual semaphores. A set of semaphores can contain up to 25 elements. Like message queues, the semaphore set creator can change its ownership or permissions. To know the count and composition of semaphore sets and understand who owns which semaphore set, administrators can use the IpcsSemaphorTest test.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
No_semaphor_set Indicates the number of semaphore sets owned by this owner. For the Total descriptor, this measure indicates the total number of semaphore sets on the server. Number This measure will be reported for the Total descriptor, only if the REPORT BY flag is set to Total or Owner and Total.

To know the complete details of each semaphore set owned by an owner and the number of semaphores each set contains, use the detailed diagnosis of this measure.

No_semaphor For each owner, this measure reports the total number of semaphores that are in the semaphore sets owned by that owner. For the Total descriptor, this measure indicates the total number of semaphores in all the semaphore sets created on the server. Number This measure will be reported for the Total descriptor, only if the REPORT BY flag is set to Total or Owner and Total.

You can compare the value of this measure across owners to know which owner owns the maximum semaphores. To know which semaphore sets are owned by such an owner, use the detailed diagnosis of the Number of semaphore sets measure.