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Preemptive Kernel and HP-UX

 
Pippo_9
Frequent Advisor

Preemptive Kernel and HP-UX

Hi all.

I've got a general question reguarding HP-UX.

I am trying to find out if HP-UX is a real full preemptive kernel o.s.

Is there anyone out there to help me?

Thanks all

Juan
2 REPLIES 2
Mark Grant
Honored Contributor

Re: Preemptive Kernel and HP-UX

I don't know about the very latest releases but I believe HPUX is described as having "preemptive points" but not fully preemptive like a proper real time OS (or Linux 2.6 for that matter).
Never preceed any demonstration with anything more predictive than "watch this"
Bill Hassell
Honored Contributor

Re: Preemptive Kernel and HP-UX

Kernel premption was a major project several years ago and most places in the kernel have preemption hooks. However, to describe any version of Unix as truly preemptive and therefore suitable for realtime process control is, well, overstated. Having spent a decade working on the HP 1000 running RTE, deterministic response times were measured in milliseconds, and with hardware microcode and a privileged interrupt card, response time to an external event would be much less that 50 microseconds. All it takes to remove realtime responses is a large swap event or a large program coredump and response time may be dozens of seconds. If I were controlling machinery, I would not even attempt to make Unix (or Windows) work unless the machines would be safe if the control computer disappeared for a few seconds.


Bill Hassell, sysadmin