> -----Original Message-----
> From: Albrecht Schlosser [mailto:firstname.lastname@example.org]=20
> Sent: July 15, 2005 6:55 AM
> To: Info-VAX@Mvb.Saic.Com
> Subject: VMS process priorities and system processes
> I'm looking for a way to give some application and server=20
> processes different=20
> highest: some server processes
> high : some other server processes
> medium : some communication processes
> low : some other processes
> lowest : client processes
> This would result in a process priority "window" of 5=20
> different priorities.=20
> These priorities should all be higher than normal=20
> (interactive) user priorities,=20
> which are by default 4. Batch priorities are still lower=20
> (from 1 to 3).
> What I'm concerned about: if I would use priorities 5-9 (or=20
> higher), then some=20
> processes would have higher priorities than some system=20
> processes, as can be=20
> seen here (from a running OpenVMS Itanium 8.2 system):
> process name state username pri/bpri image
> OPCOM HIB SYSTEM 8/ 6 OPCOM
> ERRFMT HIB SYSTEM 8/ 7 ERRFMT
> AUDIT_SERVER HIB AUDIT$SERV 10/ 8 AUDIT_SERVER
> TCPIP$INETACP HIB INTERNET 10/ 8 TCPIP$INETACP
> IPCACP HIB SYSTEM 10/ 8 IPCACP
> TP_SERVER HIB SYSTEM 10/ 8 TPSERV
> QUEUE_MANAGER HIB SYSTEM 10/ 8 QMAN$QUEUE_MANAGE
> SECURITY_SERVER HIB SYSTEM 10/ 8 SECURITY_SERVER
> JOB_CONTROL HIB SYSTEM 9/ 8 JBC$JOB_CONTROL
> TCPIP$FTP_1 LEF TCPIP$FTP 10/ 8 TCPIP$FTP_SERVER
> LATACP HIB SYSTEM 14/12 LATACP
> LANACP HIB SYSTEM 14/12 LANACP
> SWAPPER HIB SYSTEM 16/16
> I think that realtime priorities would not be needed, but=20
> what about all these=20
> processes with (base) priorities from 6 to 8, e.g.=20
> TCPIP$INETACP, IPCACP, or=20
> TPSERV. I would prefer to give lower priorities to the=20
> application processes=20
> than to these system processes, but the "window" from 4 to 6=20
> is too small.
> What do you do WRT process priorities? Raise system process=20
> priorities? What=20
> should be done (or not be done) to keep a stable and=20
> responsive system?
> Additional background information: Of course, the high=20
> priority server processes=20
> are tested well and stable, but some other processes might=20
> come into a CPU loop=20
> or similar (e.g. once there was a process with a read timeout=20
> of 0 seconds,=20
> which came from a (missing) user input timeout value :-( ).
> In such cases a system manager should still be able to log in=20
> and suspend/stop=20
> such bad behaving processes. And network activities (many=20
> processes connect via=20
> TCPIP services) should never be blocked by other processes.
> Any suggestions what to do?
It would appear that you want to ensure some processes of the same
priority do not impact other processese e.g. process runaway stuff.=20
As others have stated, you can get into trouble by purposely mixing
priorities on specific priorities.
As a suggestion, I would suggest you consider using the OpenVMS class
scheduler to do this.
Sysman> Help class
"The class scheduler provides the ability to limit the amount of CPU
time that a system's users receive by placing users in scheduling
classes. Each class is assigned a percentage of the overall system CPU
time. As the system runs, the combined set of users in a class is
limited to the percentage of CPU execution time allocated to their
Users might get some additional CPU time if the qualifier /WINDFALL is
enabled for their scheduling class. Enabling the qualifier /WINDFALL
allows the system to give a small amount of CPU time to a scheduling
class when the scheduling class's allotted time has been depleted, but a
free CPU is available."
HP Services Canada
(remove the DOT's and AT)=20
OpenVMS - the secure, multi-site OS that just works.