Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!rml
From: rml@hpfcdc.HP.COM (Bob Lenk)
Newsgroups: comp.sys.hp
Subject: Re: Masking interrupts on 9000/360's under hp-ux
Message-ID: <5570129@hpfcdc.HP.COM>
Date: 28 Feb 89 20:10:39 GMT
References: <6534@ecsvax.UUCP>
Organization: HP Ft. Collins, Co.
Lines: 25

> We have an application where we need to essentially take over full control
> of the hp 9000/360 for up to 100 millisecs....
> So we simply masked off interrupts. Can this be done under hp-ux?
> What are the possible problems? Will this cause the system to crash?
> Will this cause the system to lose clock tics? Help? Anyone?

Interrupts can only be masked by writing a custom driver.  Doing so for
100ms could have nasty effects on other I/O that might be going on (you
could certainly loose data on an ubuffered RS-232 card; I don't know the
worst possible scenario).  The system should be able to keep the system
clock up to date.

I'm not sure what the actual response time requirement is (eg. do you
need to complete Xms of processing before the next edge, which could
come as soon as Yms later?), or what else might be running on the
machine at the same time.  It's possible that a user process with
real-time priority and locked in memory could handle the job without
turning off interrupts.  Again, I'm not sure what Basic workstation
couldn't keep up without disabling interrupts; if it was also a 360
then HP-UX probably can't do any better, but if it was a 310 or a
series 200 the faster processor might be all you need.

		Bob Lenk
		hplabs!hpfcla!rml
		rml%hpfcla@hplabs.hp.com