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

[Dan Winslow <dandwinslow@gmail.com>]

On Sunday, June 13, 2021 at 11:46:23 AM UTC-5, Dan Winslow wrote:
> On Sunday, June 13, 2021 at 11:44:00 AM UTC-5, Dan Winslow wrote: 
> > On Sunday, June 13, 2021 at 8:16:31 AM UTC-5, Jeffrey R. Carter wrote: 
> > > On 6/13/21 2:06 PM, Dan Winslow wrote: 
> > > > 
> > > > Well. You are confirming that I shouldn't expect the behavior I am looking for? How does linux do in this regard, I could use it if needed. 
> > > with Xubuntu 21.04 and GNAT 11 I get 
> > > 
> > > ~/Code$ ./winslow 
> > > 8 CPUs 
> > > one 
> > > Task one done, x= 1000001 
> > > two 
> > > Task two done, y= 1000001 
> > > main done, x 1000001 y 1000001 
> > > 
> > > I get this with or without the scheduling pragma in gnat.adc. 
> > > 
> > > -- 
> > > Jeff Carter 
> > > "Don't knock masturbation. It's sex with someone I love." 
> > > Annie Hall 
> > > 45 
> > 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'. 
> > 
> > So, works perfectly on linux. Probably would on windows too if I knew how to swap out for a pthreads implementation on windows. 
> > 
> > Thanks!
> Odd that it doesn't require the gnat.adc pragma though. I suppose linux is counting on delay statements or other sync points to swap. For what I need, that's perfect.
Order of start on the two tasks is random on linux, too. It's usually task one but sometimes task 2 starts first.