Re: non-preemptive tasking on GNAT 2020 Windows 10 multicore AMD

[Dennis Lee Bieber <wlfraed@ix.netcom.com>]

On Sun, 13 Jun 2021 09:43:59 -0700 (PDT), Dan Winslow
<dandwinslow@gmail.com> declaimed the following:


>Yep, just found that myself. So, I guess since the tasks get mapped onto underlying os threads, windows has its own ideas and does things like automatic priority promotion and other non-compliant stuff. Too bad, but I guess kind of makes sense because windows does everything possible, most likely, to prevent any kind of thread monopolization. Would be nice if the gnat windows version at least threw a warning that 'hey, it's legal, but it aint gonna work on windows'.
>
	Priority promotion is a concept inherited from DEC (open)VMS, where
normal user processes had a base priority (which they never dropped below),
but would get priority boosts if it wasn't scheduled over some number of
quantums. And similarly, the top half or so of the priority range was
considered "realtime" and fixed (no priority boosting).

	Setting your program to one of Windows "realtime" levels (16-31), might
have some effect on how the program behaves since I believe those too are
fixed priority.

	Supposedly NTFS also inherited some VMS concepts -- but if so, M$
managed to obscure them from regular users.


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/