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From: carl@CITHEX.CALTECH.EDU.UUCP
Newsgroups: comp.os.vms
Subject: Re: sysgen parameters IOTA and PIXSCAN
Message-ID: <870906215448.08c@CitHex.Caltech.Edu>
Date: Mon, 7-Sep-87 00:57:39 EDT
Article-I.D.: CitHex.870906215448.08c
Posted: Mon Sep  7 00:57:39 1987
Date-Received: Tue, 8-Sep-87 01:28:47 EDT
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 > Can anyone supply information on where these are documented and what
 > they do ?  (Any other undocumented parameter information would also
 > be appreciated !)

They are documented (if nowhere else) in SYS$HELP:SYSGEN.HLB.  The following
is the help info given by sysgen:

$ SYSGEN:==$SYSGEN
$ SYSGEN HELP PAR IOTA
Parameters

  IOTA

    	(Special Parameter)
     I/O time allowance - This parameter sets the number of 10 millisecond
     units to charge the current residence quantum for each voluntary wait.
     The correct value approximates the cost of a disk I/O neglecting wait time.


$ SYSGEN HELP PI
Parameters

  PIXSCAN

    	(Special Parameter)
     PIXSCAN specifies the number of process index slots scanned per
     second for computable or computable-outswapped processes.  Such
     processes will receive an automatic priority boost for 1 QUANTUM,
     assuming that the priority of the currently executing process is not
     in the realtime range (16-31). The priority boost is implemented to
     avoid potential deadlocks, such as when a process executing below
     DEFPRI acquires a volume lock on a critical disk and cannot release
     it, because the process is unable to access the CPU.