RE: Process Control Extensions

John, All-

I think I’m in favor of the process priority “hints”, as long as it is absolutely clear in the standard that they are just
hints and that a compliant implementation is always free to ignore them.

Thanks
Stuart

From: owner-systemc-p1666-technical@eda.org [mailto:owner-systemc-p1666-technical@eda.org] On Behalf Of john.aynsley@doulos.com
Sent: Friday, May 07, 2010 4:00 AM
To: systemc-p1666-technical@eda.org
Subject: RE: Process Control Extensions

All,

Does anyone have any specific objections or counter-proposals concerning the Process Control Extensions, or is everyone positive about them as they stand? (Of course, I am not trying to rule out any improvements or clarifications as we refine the spec.)

How about ST's proposal for process priorities as hints? Adding actual process priorities to SystemC would seem to be a radical change that would impact the scheduler, process control, and might introduce the possibility of new use models. On the other hand, ST's proposal is only for "hints", in which case, do we want to change the IEEE standard "merely" to incorporate scheduler optimization hints?

Thanks,

John A


-----Stuart Swan <stuart@cadence.com> wrote: -----
To: "john.aynsley@doulos.com" <john.aynsley@doulos.com>, "systemc-p1666-technical@eda.org" <systemc-p1666-technical@eda.org>
From: Stuart Swan <stuart@cadence.com>
Date: 05/06/2010 10:05PM
Subject: RE: Process Control Extensions
John-

Some quick answers embedded below to your questions..

Thanks
Stuart

From: owner-systemc-p1666-technical@eda.org [mailto:owner-systemc-p1666-technical@eda.org] On Behalf Of john.aynsley@doulos.com
Sent: Wednesday, May 05, 2010 7:18 AM
To: systemc-p1666-technical@eda.org
Subject: Process Control Extensions
Issues/Questions

* Should we now deprecate SC_CTHREAD or keep SC_CTHREAD as a first-class feature of SystemC, or something else?
SC_CTHREAD has been around for so long that it won’t go away anytime soon. One option is to say something in the LRM such as “SC_CTHREAD
is now redundant since all of its features are now available with SC_THREAD, so SC_CTHREAD may be deprecated and removed from the standard
at some point in the future.”

* Should we invite input from the members of the OSCI Synthesis WG on the subject of clocked threads and synchronous and asynchronous resets?

* ST (Jerome) has proposed that we add process priorities. Does this P1666 WG wish to pursue that proposal? If so, how do process priorities interact with the process control extensions?

If I understood Jerome’s proposal, the priorities are just “hints” and can always be ignored. So it seems to me one option is to say that from the perspective
of the process control extensions, the priorities have no implications on the standard.

* Is include_descendants intended to find descendents of intermediate processes that have already terminated, i.e. children of dead children?
I think it is supposed to get them all, Bishnupriya needs to confirm.

* Do we need to try out these ideas in a proof-of-concept implementation, particularly given that the process control extensions are already (at least partially) implemented in the OSCI POC simulator? I will volunteer to create a set of regression tests.
We accept your offer! Having such openly available tests will be very helpful in getting the features implemented properly in all simulators.
We have donated some tests for process control constructs to OSCI. More tests are clearly needed. We have also implemented all of the constructs
in our simulator and will run any tests that people offer against our implementation and provide the log results.


John A



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