[Info-vax] Volatile, was: Re: yet another sys$qiow question

Johnny Billquist bqt at softjar.se
Fri Aug 28 20:23:59 EDT 2015


On 2015-08-29 00:11, JF Mezei wrote:
> The reason I had been given for not using ASTs and using a loop for hard
> real time was that they could ensure timing on a known event loop while
> AST delivery was unpredictable since something else could stop AST
> deliveries and delay processing etc.
>
> (Just recounting what I was told).

This don't make sense. If you want hard real time you do not want to be 
running under a generic timesharing OS to begin with. You have no idea 
what latencies you have because of operating system overhead.
You don't even know how long interrupt handling might be taking in the OS.

I can understand using polling and loops because of wanting predictable 
timing, but ASTs would not even be an alternative then, because that 
would imply a rather complex OS beneath you...

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol



More information about the Info-vax mailing list