(ipc.info.gz) semlimits

Info Catalog

(ipc.info.gz) semctl

(ipc.info.gz) Semaphores

(ipc.info.gz) Shared Memory

 
 1.6.4 Limits on Semaphore Resources
 -----------------------------------
 
 Sizeof various structures:
      semid_ds    44   /* 1 per semaphore array .. dynamic */
      sem          8   /* 1 for each semaphore in system .. dynamic */
      sembuf       6   /* allocated by user */
      sem_undo    20   /* 1 for each undo request .. dynamic */
 
 Limits :
    * SEMVMX  32767  semaphore maximum value (short).
 
    * SEMMNI  number of semaphore identifiers (or arrays) system
      wide...policy.
 
    * SEMMSL  maximum  number  of semaphores per id.  1 semid_ds per
      array, 1 struct sem per semaphore => SEMMSL =  (PAGE_SIZE -
      sizeof(semid_ds)) / sizeof(sem).  Implementation maximum SEMMSL =
      500.
 
    * SEMMNS  maximum number of semaphores system wide ... policy.
      Setting SEMMNS >= SEMMSL*SEMMNI makes it irrelevent.
 
    * SEMOPM 	Maximum number of operations in one semop
      call...policy.
 
 Unused or unimplemented:
 SEMAEM  adjust on exit max value.
 SEMMNU  number of undo structures system-wide.
 SEMUME  maximum number of undo entries per process.
 

Info Catalog

(ipc.info.gz) semctl

(ipc.info.gz) Semaphores

(ipc.info.gz) Shared Memory