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shmseg(5)							     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) mecha‐
       nism.  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  permis‐
       sions 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 system

   What Are the Side Effects of Raising the Value?
       A single process will be able to acquire more segments, possibly starv‐
       ing 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 parame‐
       ter 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 val‐
       ues.  For information about the effects of installation on tunable val‐
       ues, 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)

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