Dangers of boosting allowable shared memory in V/386 3.2.2?

Dr. Scump aland at infmx.UUCP
Wed Feb 14 13:22:27 AEST 1990


With AT&T Sys V/386 Release 3.2.2, the maximum shared memory allowed
out-of-the-box is 512K (as defined in the "mtune" file).  Our
Turbo and OnLine engines can make use of much larger amounts if
available.  Are there any hidden dangers to boosting the mtune 
constraints to allow larger values to be set in stune?  Right now,
I'm running with a SHMMAX of 8 MB (8388608) and a SHMALL of 8192,
and it appears to work OK.  This is on a 6386E/33 with 24 MB and
an unlimited user license.  (I also boosted SEMMNS to 120, if that 
matters).

Are there any potential dangers here?  The doc "recommends against"
exceeding the regular mtune limits, but they don't say why or give
guidelines for SHM* parameters in large memory configurations.

--
Alan S. Denney  @  Informix Software, Inc.       "We're homeward bound
aland at informix.com  {pyramid|uunet}!infmx!aland   ('tis a damn fine sound!)
-----------------------------------------------   with a good ship, taut & free
 Disclaimer:  These opinions are mine alone.      We don't give a damn, 
 If I am caught or killed, the secretary          when we drink our rum
 will disavow any knowledge of my actions.        with the girls of old Maui."



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