Department f Computer Engineering

Malaviya National Institute of Technology, Jaipur India

(PROM3D) Parameterized Path-Based, Randomized, Oblivious, Minimal Routing in 3D Mesh NoC

Dr. Mushtaq AhmedEmail : mushtaq@mnit.ac.in

Co-author : Rakesh kumar

TENCON’2012

Presentation layoutNetwork on ChipAdaptive Routing for Multiport 3D Mesh NoCPROM3D Routing for 3D NoCExperimental setup Results Conclusions

Why Network on Chip ?

Transistor scaling is increased◦ Millions of gates◦ Multicore architecture

Conventional bus techniques is not suitable

Require better approach i.e. Network on Chip

Tilera :TILE-Gx100 ™, 100 tilesMESH, freq 1.5GHz 45x45mm

Network on Chip

Network-on-a-Chip (NoC) is a new paradigm for System-on-Chip (SoC) design NoC consist of: Processing Elements (PE) An architecture or topology Number of Switches Network Interfaces Routing technique with an addressing system Communication Protocol for message passing

PE

RoutingNode

RoutingNode

RoutingNode

RoutingNode

RoutingNode

RoutingNode

RoutingNode

RoutingNode

RoutingNode

PE

PE

PE

PE

PE

PE

PE

PE

NoC Architectures

■ Variants of NoC architecture - Torus, Mesh, Spidergom, honeycomb, diagonalised,

HexagonUsability depend on application and performance

requirement Proper configuration is required for simulation.

■ Routing technique and performance capability:-Can vary among topology- Target is optimization of efficiency

throughput, latency, area, gitter, power

EASTWEST

NORTH

SOUTH

R1

R2

R3

R4

C1

C2

C3

C4

C5

11

12

13

14

15

21

22

23

24

25

31

41 32

42 33

43 34

44 35

45

XY

X-1,Y

X-1,Y+1

X,Y+1X+1,Y

X+1,Y-1

X,Y-1

Honeycomb

TorusMesh Spidergon

3D MeshHexagonal 2D Mesh

Routing algorithms

●Deterministic vs. Adaptive●Simplify/Complicate routing logic●Easy/Uneasy deadlock free●Prone/Robust to congestion ●Examples

●Deterministic routing (XYZ, ZXY)●Partial adaptive routing (WSF, NG, NUL, OE)

Provide the path from source to destination Two broad categories

• Deterministic and Adaptive• Deterministic routing generated

packets P from a source node S always uses uniquely determined path for bound between source and destination pair ( XYZ routing)

• Partial adaptive routing is flexible and allows to choose multiple nodes for exploring the different route for the packets generated form source destined towards reciver( West South First, North Up Last, Negative First)

Routing in NoC

XYZ Routing

Route a packet in rows first, then moves along the columns and then move along the slices toward destination

Negative First

Route a packet first adaptively west,south, and down and then adaptively east, north, and up.

West South First

Route a packet first adaptively westand south and then adaptively down, east, north, and up.

North Up Last

Route a packet first adaptively west,south, down, and east and then adaptively north and up.

PROM 3D Routing The f parameter is required in

parameterized PROM 3DLet ∆x = |Dx – Cx|, ∆ y = |Dy – Cy| and ∆ z

= |Dz – Cz| Minimum rectangle is

(∆ x +1)(∆ y +1) (∆ z +1) Overall rectangle size will be Num(rows) xNum(cols) xNum(slices).

max

rows cols   slices

( 1)*( 1)*( 1)*

(Num xNum xNum )

x y zf f

PROM 3D Routing Rules

First, boundary regions are defined Parameter f (max) is selected.Packets are pushed toward intermediary

nodes using priority functions.

Let 4*4*4 Mesh and f max =1

Source S1(1; 1; 1) and Destination D1(3; 3; 3)

f = 1* (3*3*3)/(4*4*4) = 0.42Source node Probabilities are

P1= (2+0.42)/ (2+2+2+1.26)P2= (2+0.42)/ (2+2+2+1.26)P3= (2+0.42)/ (2+2+2+1.26)

P1= 0.33, P2= 0.33 and P3=0.33Let us assume moves in x- direction

at intermediate node (2; 1; 1) where, x=1, y=2 and z=2

PROM 3D Routing: Example

At intermediate node (2; 1; 1)P1= (1+0.42)/ (1+2+2+1.26)

P2= 2/ (1+2+2+1.26)P3= 2/ (1+2+2+1.26)

P1= 0.22, P2= 0.31 and P3=0.31Here, P2 = P3 and (P2, P3 > P1).any path among P2 or P3 can be

chosen.Let it is y-ingress, i.e., y direction for

intermediate node (2; 2; 1) whereP1=0.19, P2=0.26 and P3=0.38Path from node (2; 2; 1) to node (2; 2;

2) will be selected

PROM 3D Routing: Example

At intermediate node (2; 2; 2) P1=0.23, P2=0.23 and P3=0.33. Here, P3 is higher and (P3 >

P1,P2). Path from (2; 2; 2) to node (2; 2; 3)

is selected. Again probability at node (2; 2; 3)

is to be calculated as P1=0.30, P2=0.30 and P3=0.12 where, P1 = P2 and (P1, P2 > P3).

At intermediate node (3; 2; 3) P1=0.18, P2=0.44 and P3=0. P2 is highest and path from node (3;

2; 3) to node (3; 3; 3) is selected.

PROM 3D Routing: Example

PROM 3D Routing: ExampleParameters used Values

Mesh Size 4 * 4 * 4

Packet size 20

Buffer size 8

Flit size 4

Virtual channels 2

Simulation cycles 10000

Test gen. number 2000

Traffic patterns Random and Transpose

Packet injection Bursty Data withBurst length 4 and interval of 3

Load in % 5 to 50 with 5% increasing steps

No. of simulations 10 times for each routing algo. With different load and traffic

pattern

Simulation Results

Latency under different values of fmax for random traffic with Bursty data.

Simulation Results

Latency under different values of fmax for Transpose traffic with Bursty data.

Simulation Results

Latency of XYZ, NUL, WSF, NF and PROM3D under Random traffic with Bursty data.

Simulation Results

Latency of XYZ, NUL, WSF, NF and PROM3D under Transpose traffic with Bursty data.

Results are reasonable and comparable to existing DOR routing and turn model routing algorithms, as it always tries to explore minimal path.

Parameterized PROM3D routing can handle congestion and

performs better when fmax parameter is chosen wisely.

With the higher percentage of offered load, average latency in PROM3D under random and transpose traffic is observed better, i.e., lower than other routing algorithms, as it tries to follow allowable turns within cuboid of region of interest.

Conclusions

[1] M.O. Agyeman and A. Ahmadinia. “An adaptive router architecture for heterogeneous 3d networks-on-chip”. In NORCHIP, 2011, pages 1 –4, nov. 2011

[2] Mushtaq Ahmed, V. Laxmi, and M.S. Gaur. “Performance analysis of minimal path fault tolerant routing in noc”. Journal of Electronics (China), 28:587–595, 2011.

[3] S. Akbari, A. Shafiee, M. Fathy, and R. Berangi. “Afra: A low cost high performance reliable routing for 3d mesh nocs”. In Design, Automation Test in Europe Conference Exhibition (DATE), 2012, pages 332 –337, march 2012.

[4] F. Dubois, A. Sheibanyrad, F. Petrot, and M. Bahmani. “Elevator-first: a deadlock-free distributed routing algorithm for vertically partially connected 3d-nocs”. Computers, IEEE Transactions on, PP(99):1, 2011.

References

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[6] C. J. Glass. “Adaptive routing in mesh-connected networks”. In IEEE Trans, pages 12–19, 1992.

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References

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References

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References

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