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From: SYSTEM@CRNLNS.BITNET
Newsgroups: mod.computers.vax
Subject: RE: critical section code under VMS
Message-ID: <8608130339.AA21371@ucbvax.Berkeley.EDU>
Date: Tue, 12-Aug-86 09:14:00 EDT
Article-I.D.: ucbvax.8608130339.AA21371
Posted: Tue Aug 12 09:14:00 1986
Date-Received: Wed, 13-Aug-86 06:29:46 EDT
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Don,

Critical section code is "easy" if you don't mind the overhead.
(About 700 microseconds on a 780 to convert a lock from "null"
to "exclusive", about 50% more to define or un-define it)

DEC has supplied system routines for this function:

istat = SYS$ENQW (...) to define or convert a "lock"
istat = SYS$DENQW (...) to un-define a "lock"

I have written a set of routines to simplify their use from Fortran
programs, available on request. (We use them to control access to
shared sections.)

Selden Ball

Cornell University, LNS            NYNEX: (607) 255-0688
Wilson Synchrotron Lab            BITNET: SYSTEM@CRNLNS
Judd Falls & Dryden Road            ARPA: SYSTEM%CRNLNS.BITNET@WISCVM.WISC.EDU
Ithaca, NY  14853         PHYSnet/HEPnet: LNS61::SYSTEM (node 43.251/44283)