Tru64 Unix 5.1 shm_max confirmation

From: <jeffrey.s.horvath_at_census.gov>
Date: Tue, 03 Dec 2002 15:29:45 -0500

Please confirm following:

pg 6-36 Compaq Tru64 System Configuration and Tuning "...System V shared
memory
semantics allow a maximum shared memory segment size of 2 GB minus 1 byte.
Applications that need shared memory segments larger than 2 GB can
construct these regiouns by using multiple segments. ...In addition , the
value of the shm_max attribute which specifies the maximum size of a System
V shared memory segment must be 8-MB aligned. " To accomplish this one
can set maximum value of shm_max to (2GB-8MB) = 2139095040 . "This is
maximum value (2GB minus 8MB) that one can specify for the shm_max
attribute and still share page table entries".


Does this apply whether we are using gh_chunks, rad_gh_regions or not
under 5.1 Tru64
Unix.? Is this indeed a System V shared memory limitation and does it
still apply under 5.1 Tru 64? Also, why does sysconfig -Q ipc show a very
large value for shm_max if one can only set it to 2GB?

Thanks,
Received on Tue Dec 03 2002 - 20:30:34 NZDT

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