Re: [sv-ec] Scheduling algorithm discussions

Arturo Salz wrote:
> Gord,
> 
> Your write-up does a good job at capturing the two options we 
> discussed during the meeting. I wanted to add clarify some of
> the issues you raised in the message.
> 
[...]
> However, the #0 anomaly is easily addressed by the addition of another 
> region, a Reactive-Inactive (pardon the oxymoron) into which programs 
> can post #0 events. 

Right -- the Reactive-Inactive is exactly what I included in
Approach II.  Approach II includes reactive-inactive AND
reactive-NBA to mimic the design iteration regions.  The
post-reactive-NBA is what you are calling the reactive-NBA.

Definitely a bit confusing.

The Approach II writeup was meant to be the most general form
of the algorithm.

 > This would leave the interaction between "program"
> processes and "design" processes (caused by calls to side-effecting tasks 
> or functions in the design from within programs) as the only observable 
> difference between the two approaches. In this sense I believe that both 
> approaches are approximately comparable --- both approaches require the 
> addition of at least two regions (Reactive and Reactive-Inactive) to provide 
> atomic write-back of values from programs to the "design" and equivalent
> behavior for #0 events.
> 
> Approach II proposes that we retain post-Reactive-NBA in order to
> propagate values from the program back to the design. However, that
> region is not strictly needed. Given that this approach requires that all
> Reactive regions be processed before looping back to the design regions,
> we could just as easily post all program-to-design NBAs in the regular
> (design) NBA region. This has a nice property (IMHO) of treating all
> NBA's into the design in the same way, regardless of whether the origin
> of the NBA is a program or a module. 

Yes.  This option is exactly why I sent the follow-up this morning.
If we strike what I called the "reactive-NBA" and have just the
reactive / reactive-inactive regions then we are left with the choice
of whether we want to allow pending active region activations to
occur due to side-effect assignments BEFORE doing the NBAs or
whether we want the program NBAs to happen first.  If we don't
have the post-reactive-NBA region, side-effect assignments fully
propagate before the NBAs are seem; if we have the post-reactive-NBA
region, the NBAs occur before any activated design processes.

I can make consistency arguments either way.

Gord.


 >  As I pointed above, this slight
> adjustment to approach II requires only two Reactive regions: Reactive
> and Inactive. The additional Reactive-NBA region could be added to
> support program-to-program NBA's, which are currently not allowed.
> 
>     Arturo
> 
> ----- Original Message ----- 
> From: "Gordon Vreugdenhil" <gordonv@Model.com>
> To: "SV_EC List" <sv-ec@eda.org>
> Sent: Friday, April 29, 2005 4:07 PM
> Subject: [sv-ec] Scheduling algorithm discussions
> 
> 
> The attached file describes my understanding of the scheduling
> algorithms that were discussed today.  Anyone on the call, please
> feel free to modify, extend, or correct this.
> 
> Gord.

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Gordon Vreugdenhil,  Staff Engineer               503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com