Architetturale synthesis

1) architetturale Synthesis:

It concurs to construct to the macrocospic structure of a digital system them to leave from its expressed behavioural description through a graph sequenziale, with of resources and with of ties.

 

2) Date path:

Draft of the interconnection of resources and logic of connection.

 

3) Classification of the resources:

to)       Resources it works them concur to execute logical operations arithmetical, they are subdivided in resources works them primitive that is common to many applications and resources work them specific of one determined application.

b)       Resources of memory concur the memorization of the data.

c)       Resources of interface which the buses that render the transfer of the data possible.

 

4) Typology of ties:

to)       Ties of implementation they demand to the synthetized system determined property, as an example often one demands a limited area and a time of execution very determined.

b)       Ties of interfacciamento legacies to the necessity of interfacciare the system with other systems, the format of the data and their synchronization are important with regard to this.

 

5) It is made of the architetturale synthesis:

to)       Scheduling of the operations

b)       Binding of the resources

The limitations taxes on one of the two are made of the synthesis ripercuotono also on the other phase and viceversa.

 

6) Model for the problems of scheduling:

A graph is used directed acyclic in which the operations are represented from concern to us while it arches to it represent the dependencies, to every operation then are associated an execution delay d that it is null only for the apex source and the apex destination, the delays are contained in a D carrier while the cycle of clock in which it begins the operation is contained in a T carrier and it is assumed that the operation of the apex source beginnings to the cycle of clock 1.

 

7) Latenza:

It is the time that elapses between the beginning of the operation of the apex destination and that one of the apex source, it is equal to the longest way between source and destination.

 

8) not bound Scheduling:

The moments of execution of the operations come programmed without to have ties on the resources, are because these can be dedicated, are because the operations can once be taken advantage of serializzando that the resources have been fixed. Draft of algorithms is used you mostly in order to gain the latenza of problems with limitations.

 

9) Algorithm ASAP:

As Soon Possible As, the operation comes not hardly schedulata all the operations on which it depends have been executed.

 

10) Algorithm ALAP:

As Late Possible As, the operation comes schedulata the latest possible this to the aim to characterize a advanced limit for the latenza.

 

11) Mobility of an operation:

It is difference m between its schedulazione of operazione with algorithm ALAP and a schedulazione of the same one with algorithm ASAP.

 

12) bound Scheduling from the time:

The time limitations come specified like advanced limit and inferior al time of separation between two instructions, is represented by means of a graph bound that is obtained dal graph sequenziale (…weighed with the execution delays delle operations) adding an arc in ahead with equal weight al limit minimal nel case wants to impose the minimal limit of time between the two operations while if we want to impose the maximum limit behind becomes part nel graph an arc on the credit side with opposite equal weight on the credit side del the maximum limit. A possible criterion of scheduling consists in considering to every turn time the maximum limit and to verify that not there are positive cycles you.

 

13) bound Scheduling from the resources:

The algorithms of scheduling that they demand to diminish the latenza with resources limited or to diminish the resources with limited latenza are intrattabili, the heuristic algorithms of list.scheduling give some of the approximate solutions. They come introduces three algorithms to you:

to)       Minimizzazione of the latenza with limit of the resources

To all operations come associated delay unitary, resources are in number prestabilito and diagram is weighed with priority so that the operations that must be executed for first more have elevated priority, proceeds schedulando before operations to priority more elevated compatibly with number of resources, if then there is a resource that to a data cycle of clock remains made unusable, comes assigned to the relating operation having greater priority to them.

b)       Minimizzazione of the resources with latenza limit

A resource for every type of operation is had initially, comes schedulate the operations with mobility zero that is those that if schedulate do not determine the violation of the limit on the latenza, to such necessary aim if come added of the resources. The remaining operations come only schedulate if they do not demand resources adds them.

c)       Force Directed Scheduling

The interval of mobility of an operation characterizes the cycles in which the same one can be schedulata, is gained like difference between its schedulazione with the ALAP and with the ASAP, the probability that the operation comes schedulata to outside of this interval it is null while he is constant and inversely proporziona they to the amplitude of the interval to its inside. Adding the distribution of probability for operations of the spread type a diagram of the distribution of probability for every type of operation is obtained, the operation prechoice for being schedulata on one given resource to the step n is prechosen so that the forces are opposed and wins more strongly.

 

14) Binding of the resources:

The binding it is face to make that more operations can have use of of the same resource to the aim to reduce the area of the circuit, are the following typology of binding:

to)       correspondence biunivoca between type of operation and type of resource

b)       different operations executed on same resource (…as an example the ALU)

c)       a same operation can be executed on more resources (… summary with various characteristics)

The problem can be set up in terms of coloration of the graph of the constructed incompatibilità inserting an arc between the operations that are incompatible in how much demand the same resource in the same moment of time.

 

15) Sharing of the resources does not work them:

For resources it does not work them agrees the memory as an example in which they come memorizzate the variable ones that are characterized from a time of life, evidently can be carried out a binding also in order regolamentar of the sharing of the registries in which memorizzate the variable ones.