UNIVERSITA’ POLITECNICA DELLE MARCHE, ANCONA (ITALY) Massimo Conti, Giovanni Vece TRANSACTION LEVEL POWER ANALYSIS WITHIN SYSTEMC/TLM APPLICATIONS 22

UNIVERSITA’ POLITECNICA DELLE MARCHE, ANCONA (ITALY)

Massimo Conti, Giovanni Vece

TRANSACTION LEVEL POWER ANALYSIS

WITHIN SYSTEMC/TLM APPLICATIONS

22. European SystemC User’s Group Meeting, September 14th, 2010, Southampton

INTRODUCTORY OVERVIEW

• PKtool (Power Kernel tool) is a power analysis tool developed by Università Politecnica delle Marche.

• Mainly dedicated to power estimations for systems modelled in SystemC/C++ language.

• Entirely realized in SystemC/C++, as a language extension for power analysis.

• Recently refined for transaction level power estimations in application with the SystemC TLM 2.0 framework.


MAIN MOTIVATIONS

Power dissipation represents a primary design issue, making it

worthwhile to explore possible SystemC extensions for power

analysis.

Providing an istrument for direct power analysis within

a SystemC-based design, Promoting the diffusion and use of the SystemC language.

basic language

verification library

AMS extension

TLM framework

customized user extensions

SystemC power analysis extension


APPLICATION MODALITIES

• PKtool can be applied on the single sc_modules constituting a SystemC

description.

• The simulation results are given by the power/energy estimations of each monitored sc_module, reported in apposite text files.

sc_module #1

sc_module #4

sc_module #3

sc_module #2

SYSTEMC DESCRIPTION

SIMULATION RESULTS

PKTOOL SIMULATOR

POWER ESTIMATION

#1

POWER ESTIMATION

#2

POWER ESTIMATION

#3


INSTANCE OF POWER_MODULES

sc_module #1

sc_module #4

sc_module #3

sc_module #2

ORIGINAL SYSTEMC DESCRIPTION

SYSTEMC DESCRIPTION WITH POWER_MODULES

power_module

#1

power_module #4

power_module #3

power_module

#2

POWER_MODULE

INSTANCE


• Instance example :

master m1, m2; POWER_MODULE(master) m1,m2;

POWER MODELS IN PKTOOL ENVIRONMENT

• Formal representations of the power dissipated by a digital system (usually an approximation of the real dissipation).

• PKtool handles power models through a behavioural interface of general validity.

• PKtool makes available several power models included inside a default model library.

signal-based power models

table-based power models

operator-based power models

transaction level power models

PKtool model library


SYSTEMC DESCRIPTION WITH POWER_MODULES

power_module

#1

power_module #4

power_module #3

power_module

#2

POWER MODEL SELECTION

• Each power_module is associated to power models of the PKtool model library.

• The association task is carried out via an interactive procedure, at the beginning of a simulation.

PKTOOL MODEL LIBRARY

power model

#1

power model

#2

power model

#4

power model

#3


PKTOOL SIMULATION FLOW

• A PKtool simulation takes place during an ordinary SystemC simulation of the system.

• The power estimations are referred to the system evolution reproduced in the SystemC simulation.

powerestimation

Start of SystemCsimulation

End of SystemCsimulation

time

PKtool simulation

SystemC simulationmodeldata

powermodel

modeldata


EXTENSION FOR TRANSACTION LEVEL POWER ANALYSIS (PKTOOL/TLM)

• The latest PKtool evolution has led to an extension for transaction level power estimations.

• Applicable on system models realized through the TLM 2.0 framework of SystemC language (SystemC/TLM) .

• Conceptually derived from research studies on estimation methodologies at transaction level.

• Analysis modalities fitting the simulation modalities in SystemC/TLM.


IMPLEMENTATION APPROACH

• BENEFITS: unified design context, no need of ad hoc execution tools,, . wide chances for interoperability and user enhancements,

C++ language standard

SystemC basic language

SystemC/TLM

Basic PKtool

PKtool/TLM framework

PKtool/TLM is implemented according to a typical SystemC modeling paradigm:


MODULE INTERACTIONS IN SYSTEMC/TLM

• Communications based on interface function calls.

• Logical roles: initiator, target, interconnect unit.

• Functional roles: caller, callee.

Initiator TargetInterconnectcomponent


TRANSPORT INTERFACES IN SYSTEMC/TLM

Transport Interfaces Functions

tlm_blocking_transport_if b_transport(.)

tlm_fw_nonblocking_transport_if nb_transport_fw(.)

tlm_fw_nonblocking_transport_if nb_transport_bw(.)

tlm_fw_direct_mem_if get_direct_mem_ptr(.)

tlm_fw_direct_mem_if

invalidate_direct_mem_ptr(.)

tlm_transport_dbg_if transport_dbg(.)


ESTIMATION APPROACH AT MODULE LEVEL

• An interface function call implies an energy dissipation for the caller and callee

modules.

• The overall energy dissipation of a module can be estimated as the sum of the

energy costs of the related function calls.

CALLERMODULE

CALLEEMODULE

Interface function . call

energy dissipation

energy dissipation


ASSOCIATION BETWEEN INTERFACE FUNCTIONS AND

POWER MODELS

b_transport( )

nb_transport_fw( )

nb_transport_bw( )

…

…

SYSTEMC/TLMMODULE

power model

power model

power model

INTERFACE FUNCTIONS


POWER MODELS IN PKTOOL/TLM

• PKtool/TLM provides some transaction level power models directly applicable in power estimations.

• Targeted to estimate the energy dissipation of an interface function call.

• Conceptually derived from estimation methodologies at transaction level.

• Application modalities fitting with the simulation dynamics in SystemC/TLM.


FORMULAS APPLIED FOR POWER ESTIMATIONS

The overall energy estimation of a monitored module is achieved through the following formulas:

1) basic: Emod =

2) more complete: Emod = +

N = function calls Ei = energy dissipations per function call

Pst = static power dissipation M = idle periods Tj = idle times

ΣN

i =1

Ei

Σi =1

Ei

Σj =1

Pst Tj

M

idle idleactivephase

activephase simulation

time


N

CONFIGURATION STEPS FOR PKTOOL/TLM ANALYSIS

• A system module can be configured for PKtool/TLM analysis through the following main steps:

a) definition and istance of a related power_module.

b) selection of the interface functions to be monitored.

c) specification of a power model for each selected functions.

• The steps a) and c) are carried out with the same modalities of a basic PKtool analysis.


SELECTION OF INTERFACE FUNCTIONS /1

The selection of an interface function distinguish two possible cases:

1) Functions concerning the module as callee.

POWER_MODULE_CLASS(example_mod) { ... ...

PK_NB_TRANSPORT_FW_2

PK_GET_DIRECT_MEM_PTR_2

}

Select the functions nb_transport_fw(.) and get_direct_mem_ptr(.)

implemented by the module


SELECTION OF INTERFACE FUNCTIONS /2

2) Functions concerning the module as caller.

SC_MODULE(example_mod) { ... tlm::tlm_initiator_socket<> init_sock; } POWER_MODULE_CLASS(example_mod) { ... ... PK_NB_TRANSPORT_FW_1(target_sock) }

Select the functions nb_transport_fw(.) called via init_sock


ANALYSIS RESULTS /1

• At the end of a PKtool/TLM simulation, the analysis results are reported in distinct text files.

• Each result file is associated to a specific power_module.

• Example:

overall simulation period: [0 - 184467 ps]

POWER/ENERGY DISSIPATION OF IMPLEMENTED TLM FUNCTIONS

function: nb_transport_bw

function calls = 128

energy estimation = 1.53e-005 J

average power estimation = 8.32e-013 W


ANALYSIS RESULTS /2 POWER/ENERGY DISSIPATION OF SOCKET TLM FUNCTIONS

SOCKET: initiator_socket

function: b_transport




function: nb_transport_fw




STATIC DISSIPATION

energy estimation: 1.844e-005J

OVERALL ENERGY ESTIMATION: 9.36e-005J

PKTOOL REFERENCES ON THE WEB


• PKtool/TLM will be soon distributed as free of charge open source releases

• Downloadable from:

http://www.deit.univpm.it/PKtool

• Included in the release PKtool 2.2 beta-8

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UNIVERSITA’ POLITECNICA DELLE MARCHE, ANCONA (ITALY) Massimo Conti, Giovanni Vece TRANSACTION LEVEL POWER ANALYSIS WITHIN SYSTEMC/TLM APPLICATIONS 22