hpux man page for shmseg

shmseg(5)							File Formats Manual							 shmseg(5)

NAME
       shmseg - maximum number of System V shared memory segments per process

VALUES
   Default
   Allowed values
       Maximum: Any value less than or equal to

DESCRIPTION
       Shared  memory is an efficient InterProcess Communications (IPC) mechanism.  One process creates a shared memory segment and attaches it to
       its address space.  Any processes looking to communicate with this process through the shared memory segment then attach the shared  memory
       segment to their corresponding address spaces.  Once attached, a process can read from or write to the segment depending on the permissions
       specified while attaching it.

       This tunable sets an upper limit to the number of segments which can be attached per process.

   Who is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Changes to this tunable take effect immediately.

   When Should the Value of This Tunable Be Raised?
       If user processes reach their limit, more segments are desired, and the current value is less than the total number of segments in the sys-
       tem

   What Are the Side Effects of Raising the Value?
       A single process will be able to acquire more segments, possibly starving another process which previously was able to acquire all the seg-
       ments it needed.  In this case, should be raised if it is below it's maximum.

   When Should the Value of This Tunable Be Lowered?
       This tunable should only be lowered to enforce segment policy on user processes, or if one runaway process is  hogging  the  global-segment
       pool.  Otherwise, keeping the maximum higher than the common usage is harmless.

   What Are the Side Effects of Lowering the Value?
       None.

   What Other Tunable Values Should Be Changed at the Same Time?
       should be considered, as previously described.

WARNINGS
       All  HP-UX kernel tunable parameters are release specific.  This parameter may be removed or have its meaning changed in future releases of
       HP-UX.

       Installation of optional kernel software, from HP or other vendors, may cause changes to tunable  parameter  values.   After  installation,
       some  tunable  parameters may no longer be at the default or recommended values.  For information about the effects of installation on tun-
       able values, consult the documentation for the kernel software being installed.	For information about optional kernel  software  that  was
       factory installed on your system, see at

AUTHOR
       was developed by HP.

SEE ALSO
       shmmni(5).

							     Tunable Kernel Parameters							 shmseg(5)