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The tstshm (test shared memory) utility can be used to evaluate the shared memory configuration of a Unix or Linux system. The output may also be useful if you want to relocate the SGA to a different location in memory. This utility can be found in the server's ORACLE_HOME/bin directory.

Information provided[edit]

Tstshm provides the following information:

  • The number of segments of shared memory generated and attached to the process
  • The location of the shared memory in virtual memory
  • The size of shared memory
  • The size of the largest single segment

Sample output[edit]

$ tstshm
Number of segments gotten by shmget() = 50
Number of segments attached by shmat() = 50
Segments attach at lower addresses
Default shared memory address = 0xb6c5f000
Lowest shared memory address  = 0xb6c5f000
Highest shared memory address = 0xb6c5f000
Total shared memory range     =  2097152
Total shared memory attached  = 104857600
Largest single segment size   =  2097152
Segment boundaries (SHMLBA)   =     4096 (0x1000)