abstract models of noc-based mpsocs for design space exploration
abstract models of noc-based mpsocs for design space exploration
abstract models of noc-based mpsocs for design space exploration
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NoC generation<br />
1<br />
Traffic<br />
Generation<br />
traffic temporal<br />
distribution<br />
2<br />
File internal view<br />
(each line represents a<br />
packet)<br />
20!! Available!in:!http://www.jdom.org/.!!<br />
!<br />
!<br />
ATLAS Design Exploration Flow<br />
3<br />
NoC Simulation Traffic Evaluation<br />
RTL / Ptolemy II<br />
Simulation<br />
Input files<br />
P "<br />
C "<br />
Output files<br />
R<br />
"<br />
R<br />
"<br />
timestamp target pkt_size source data<br />
timestamp target pkt_size source data<br />
timestamp target pkt_size source data<br />
timestamp target pkt_size source data<br />
timestamp target pkt_size source data<br />
P "<br />
R<br />
"<br />
NoC<br />
model<br />
R<br />
"<br />
"<br />
C<br />
P: producer<br />
C: consumer<br />
R: router<br />
Figure!26!!S!ATLAS!<strong>design</strong>!<strong>exploration</strong>!flow.!<br />
traffic analysis<br />
module<br />
4<br />
graphics / reports<br />
generation<br />
5<br />
NoC Power Evaluation<br />
graphics / reports<br />
generation<br />
Step/ 1! comprises! the! NoC! configuration! (e.g.! specification! <strong>of</strong>! buffer! depth,! routing!<br />
algorithm)! and! generation.! In! this! step! two! NoC! <strong>models</strong>! (with! the! same! configuration)! are!<br />
generated:!HERMES!(RTL!description)!and!an!actorSoriented!model!(XML!description!<strong>of</strong>!RENATO!or!<br />
JOSELITO).!The!MAIA!tool!is!used!<strong>for</strong>!HERMES!generation![OST05],!while!the!actorSoriented!model!<br />
is! generated! by! a! developed! tool! <strong>based</strong>! on! the! API! JDOM 20 .! Step/ 2! generates! different! traffic!<br />
patterns,!<strong>for</strong>!different!injection!rates!and!source/target!pairs!(e.g.!random!and!complement).!As!<br />
described!in![TED05],!one!important!concept!in!traffic!modeling!is!the!packet!timestamp,!which!<br />
defines!the!ideal!moment!that!a!packet!should!be!inserted!into!the!NoC!by!the!source!PE!(P!in!<br />
Figure! 26).! The! packet! timestamp! is! calculated! according! different! temporal! traffic! distribution!<br />
(e.g.!normal!and!uni<strong>for</strong>m).!All!generated!traffic!files!(step/2)!are!interpreted!and!injected!to!the!<br />
NoC!by!producers!(P),!in!step/3.!The!HERMES!NoC!is!simulated!using!ModelSim®!(RTL!simulation),!<br />
while!actorSoriented!NoC!<strong>models</strong>!are!simulated!in!Ptolemy!II!framework.!!During!the!simulation,!<br />
consumers! (C)! generate! output! files! that! are! read! by! the! traffic! analysis! module,! when! the!<br />
simulation! finishes! (step/ 4).! ! The! traffic! analysis! module! verifies! if! all! packets! were! correctly!<br />
received,! and! generates! basic! statistic! data! (e.g.! a! report! file! and! graphics)! concerning! time! to!<br />
deliver! packets! (step/ 5).! The! report! file! presents! some! traffic! analysis! results,! such! as:! (i)! total!<br />
number!<strong>of</strong>!received!packets,!(ii)!average!time!to!deliver!the!packets,!in!clock!cycles,!(iii)!total!time!<br />
to! deliver! all! packets,! in! clock! cycles,! and! (iv)! the! average,! minimal,! maximal! and! standard!<br />
deviation!time!to!deliver!a!packet,!in!clock!cycles.!The!step/6!uses!a!module!called!HEFESTUS!to!<br />
generate!NoC!power!results!(e.g.!power!reports).!<br />
4.5.1 Experimental Setup<br />
This!Section!presents!simulation!results!<strong>of</strong>!the!implemented!model!obtained!according!to!<br />
the! validation! process! described! below.! The! NoC! Models! (HERMES,! RENATO! and! JOSELITO)! are!<br />
evaluated!varying:!<br />
• NoC!sizes:!2x2,!3x3,!4x4!and!5x5;!<br />
6<br />
59
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