[mod.computers.vax] critical section code under VMS

SYSTEM@CRNLNS.BITNET (08/12/86)

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
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