
PSDFDirector |
ptolemy.domains.psdf.kernel.PSDFDirector |
The Parameterized Synchronous Dataflow (PSDF) domain is an
extension of the Synchronous Dataflow (SDF) domain that allows for
more extensive reconfiguration of models. The SDF domain uses
static analysis of variable dependence to detect cases where rate
parameters may change. By default, SDF disallows reconfiguration
of all rate parameters. If rate parameters are allowed to change,
then SDF checks that rate parameters do not change during execution
of the schedule, and declares that inferred rate parameters for
external ports change as often as the internal rate parameters.
<p>This domain offers two key extensions:
<ol>
<li> Dependence analysis is used to determine if the modification to the
rate parameters occurs during execution of the SDF schedule. If
this test passes, then a parameterized schedule is constructed.
<li> The generated schedule is checked for local synchrony, to determine
if external rate parameters may change. The correct dependency
information for external ports is then declared.
</ol>
Note that the resulting behavior is identical to the SDF scheduler,
with rate parameter changes allowed, except much more efficient, since
scheduling on the fly is not necessary during every reconfiguration.
Additionally, code can be generated for the PSDF domain that allows
for efficient reconfiguration. The added precision of dependency analysis
for external rate parameters also means that some hierarchical models that
would be ruled out by the SDF checks are allowed.
Author(s): Steve Neuendorffer
Version:$Id: PSDFDirector.doc.html,v 1.1 2006/02/22 18:41:22 mangal Exp $
Pt.Proposed Rating:Red (neuendor)
Pt.Accepted Rating:Red (johnr)