Design Productivity Crisis

Design Productivity Crisis

Communication Modeling for System-Level Design Andrew B. Kahng#,* [email protected] Kambiz Samadi* [email protected] CSE# and ECE* Departments, UCSD November 24, 2008 Outline Motivation Communication Synthesis for Network-on-Chip Network-on-Chip Architecture Modeling Buffered Interconnect Model Router Power and Area Model Bus Architecture Modeling Conclusions ISSOC-2008 2 Motivation Focus of design process is shifting from computation to communication Device and interconnect performance scaling mismatches cause breakdown of traditional across-chip communication

System-level designers require accurate, yet simple models to bridge planning and implementation stages Todays system-level performance, power modeling suffers: Ad hoc selection of models Poor balance between accuracy and simplicity Lack of model extensibility across future technology nodes Due to design performance / power constraints, early-stage design exploration has become crucial Our Goal: Develop accurate models that are easily usable by system-level design early in the design cycle ISSOC-2008 3 Communication Synthesis for Network-on-Chip Given An input specification as a set of communication constraints A library of communication components An objective function (e.g., power, area, delay) Find A network-on-chip implementation as a composition of library components that Satisfies the specification Minimizes the cost function Communication Synthesis Infrastructure (COSI) Based on the Platform-Based Design methodology Takes specification and library descriptions in XML format Produces a variety of outputs, including a cycle accurate

SystemC implementation of the optimal network-on-chip ISSOC-2008 4 Constraint-Driven Communication Synthesis Synthesis Application Point-to-Point Specification Implementation Perf. / Cost Abstractions Constraints Propagation On-Chip Communication Library Synthesis Result ISSOC-2008 5 Buffered Interconnect Model Inputs for repeater delay calculation Components

Delay and slew values for a set of input slew and load capacitance values Repeater model (obtained fromdelay Liberty / SPICE) Input capacitance for different (Liberty, PTM) Separate models for repeater intrinsicsize delay, output Inputs for wire delay calculation capacitance slew, input Wire dimensions (ITRS/PTM, LEF, ITF) Wire delay model Inter-wire spacings for global and intermediate layers (ITRS/PTM, LEF, ITF)

Inputs for power calculation Accounts for coupling capacitance impact on wire delay Input capacitance (Liberty, PTM) Repeater Wire parasiticspower (computedmodel in wire delay calculation) Accounts for sub-threshold and gate leakages Device Interconnect Automatic Interconnect Repeater . lib area model Extraction Min. Inverter T Automatic Derived Rd HILD from existing cell layouts (can be extrapolated)

LEF/ITF Extraction MASTAR Cin Wmin Wire area model Interconnect ITRS Ioff Smin Chapter Derived from wire width and spacing SPICE(can Sim. be extrapolated) tintrinsic ILD PTM TIERS(L,I,SG,G) Global Local Intermediate Semi-global Technology parameter extraction flows. ISSOC-2008 6 Repeater and Wire Models Intrinsic Delay Model i(slewin)

Drive Res Model r(slewin) delay = i(slewin) + r(slewin) * CL r(s) = f(size, slewin) slewout = f(slewin,CL) wire delay = Elmore Repeater area and power linear with repeater size Predictions extend down to 16nm Delay model is < 15% of PrimeTime ISSOC-2008 7 Impact on System-Level Design Testcases VPROC: video processor with 42 cores and 128-bit datawidth dVOPD: dual video object plane decoder with 26 cores and 128-bit datawidth 2 Dynamic Power (mW) Leakage Power (mW) Total Area (mm ) SoC Orig. Prop. Orig.

Prop. Orig. Prop. 90nm 117.3 364.8 38.1 99.6 0.37 0.346 VPROC 65nm 51.1 179.9 69.9 86.7 0.217 0.223 90nm 63.4 88 14.2 32.5 0.141 0.162 dVOPD 65nm 27.3 73.2 25.7 33.2 0.082 0.085

Original model (Orig.) underestimates power compared to the Proposed Model (Prop.) Avg # hops Orig. Prop. 3.09 3.01 3.1 3.42 1.76 1.76 1.76 1.91 Max # hops Orig. Prop. 4 5 4 6 3 3 3 4 Original Model is very optimistic in delay becomes more critical as technology scales and the chip size becomes larger ISSOC-2008

8 ORION2.0: Accurate NoC Router Models circuit implementation & buffering scheme architectural parameters # of ports; # of buffers # of xbar ports; # of VC SRAM and register FIFO MUX-tree and Matrix crossbar voltage, frequency different arbitration scheme hybrid buffering scheme Area Leakage FIFO Arbiter Crossbar Clock Link technology parameters interconnect parameters device parameters scaling factors for future technologies

ORION2.0 NEW ! Dynamic Built on top of ORION1.0 Provides, previously missing, power subcomponents Provides significant accuracy improvement vs. ORION1.0 Uses our automatic flows to obtain technology inputs To appear in DATE-2009 (A. B. Kahng, B. Li, L.-S. Peh, and K. Samadi) 9 ISSOC-2008 Validation and Significance Assessment Validation: Two Intel NoC Chips (1) Intel 80-core Teraflops, and (2) Intel SCC ORION2.0 offers significant accuracy improvement Intel 80-core v1.0 v2.0 %diff (total power) -85.3 %diff (total area) -80.9 -19.4 -23.6 Intel SCC

v1.0 v2.0 +202.4 +20.47 +31.87 +26.37 System-level Impact: COSI-OCC ORION2.0 models lead to better-performing NoC: (1) less # hops, and (2) less # routers Relative power due to additional port not as high in ORION2.0 vs. 1.0 SoC P (mW) v1.0 v2.0 VPROC 0.875 dVOPD 0.412 2 A (mm ) v1.0 v2.0 # routers v1.0 v2.0 0.924 2.043 2.329 0.486 1.217 1.343

33 18 ISSOC-2008 25 16 max. # router ports v1.0 v2.0 8 6 12 6 max. # hops v1.0 v2.0 6 11 5 10 10 AMBA Models

Signal Bus Modeling: system-level interconnect model (described earlier) Logic Modeling (multiplexers, decoders, and arbiter): Block latency based on gate delay model (cf. Carloni et al. ASPDAC08) Dynamic power is computed after measuring the switching capacitance Leakage power is computed from average device leakages Area is computed from cell areas of logic gates ISSOC-2008 11 AMBA Modeling and Bus vs. NoC Study Delay, power, area models within 11% of physical implementation Functional forms verified against physical implementation of AMBA-AHB controller Bus vs. NoC study enables design space explorations of heterogeneous communication fabrics Area

Delay Dynamic AMBA Model technology & design style Leakage floorplan transaction min. width, spacing, thickness dielectric thickness, constant read and write device drive res, cap, leakage length width/spacing, buffering scheme address progression ISSOC-2008 location of all masters, slaves bit widths of all masters, slaves optionally, locations of arbiter, decoder, and multiplexers 12 Conclusions and Future Directions Accurate models can drive effective system-level

exploration Reproducible methodology for extracting inputs to models Modeling at different levels of abstractions protocol encapsulation (e.g., hand-shaking for AMBA bus allocation) buses, pipelined rings (e.g. EIB in IBM Cell) routers, network interfaces FIFOs, queues, crossbar switches (ORION2.0) Extending to other technologies 3D IC integration (i.e., TSV modeling, multi-layer router modeling, etc.) ISSOC-2008 13 Backup Slides ISSOC-2008 14 Communication Synthesis Key Elements Specification of input constraints Set of IP cores: area and interface End-to-end communication requirements between pairs of IP cores: latency and throughput Characterization of library of components Interface types, max number of ports

Max capacities: bandwidth, latency, max distance Performance and cost model Component instantiation and parallel composition Rename, set parameters of library components Composition based on algebra on quantities (including type compatibility) ISSOC-2008 15 Communication Synthesis Example Synthesis of optimal network-on-chip Return valid composition that meets input constraints and Minimizes the objective function (e.g., power dissipation) (Original Specification) Platform Instance 2 Platform Instance 1 ISSOC-2008 16 COSI: Communication Synthesis Infrastructure COSI is a public-domain software package for NoC synthesis ISSOC-2008

17 Dynamic and Leakage Power Models Dynamic Power: Switching Capacitance Clock power: Pclk = CclkVdd2f Cclk = Csram-fifo + Cpipeline-registers + Cregister-fifo + Cwiring Physical Links: due to charging and discharging of capacitive load Pd = CloadVdd2f; Cload = Cground + Ccoupling + Cinput Register-based FIFO: implemented as shift registers Other components: we use ORION 1.0 models Leakage Power: Subthreshold and Gate From 65nm and beyond gate leakage becomes significant Isub(i,s) and Igate(i,s) are subthreshold and gate leakage currents per unit transistor width for a specific technology Wsub(i,s) and Wgate(i,s) are the effective widths of component i at input state s for subthreshold and gate leakage, respectively Key circuit components INVx1, NAND2x1, NOR2x1, and DFF ' ' Ileak ( Block ) = Prob( i , s ).(Wsub ( i , s ).Isub

( i , s ) + W ( i , s )gate I gate ( i , s )) i s ISSOC-2008 18 Area Model As number of cores increases, the area occupied by communication components becomes significant (19% of total tile area in the Intel 80-core Teraflops Chip) Gate area model by Yoshida et al. (DAC04) Link area model by Carloni et al. (ASPDAC08) We model FIFO, crossbar switch, and arbiter areas using the adopted gate area model Areaarbiter = (AreaNOR2x1.2(R-1)R) + (AreaDFF.(R(R-1)/2)) + (AreaINVx1.R) ISSOC-2008 Matrix Arbiter 19

Recently Viewed Presentations

  • Effective Conservation Fish and Wildlife Service roles in

    Effective Conservation Fish and Wildlife Service roles in

    The Sikes Act is the fundamental linchpin for the success of the Department of Defense's Natural Resources Conservation Program. − John Conger. This is a quote from the 2014 Sikes Act reauthorization hearings in Congress. John Conger was theActing Assistant...
  • Deploying and Maintaining Smart Client Applications

    Deploying and Maintaining Smart Client Applications

    部署和维护智能客户端程序 Name Title Microsoft Corporation 日程 智能客户端的 "部署3大要素" 深入: 部署的设计选择 无接触部署选项 随程 .
  • Communication Overview What is communication? Internal and external

    Communication Overview What is communication? Internal and external

    Communication Freepost Special envelopes where customers can reply to business & they pay the postage. Private telecommunications providers Eircom BT Perlico Orange Meteor Vodafone Telecommunication services Telephones Freefone Texting Answering service MODERN METHODS OF COMMUNICATION Internet E-mail www Teleconferencing Up...


    Rebeca Vara Cilla. Dra. Marly Pierina Rubio Sierra. Contexto Clínico ♂ 14 años. Traumatismo deportivo "caída sobre pie izquierdo tras voltereta hacia delante" Tumefacción y deformidad en tercio medio de tibia. Dolor y crepitación a la palpación. Rx : Fractura...
  • 11/11/2017 Dr. Geoffrey Wango Counselling Psychology University of

    11/11/2017 Dr. Geoffrey Wango Counselling Psychology University of

    Dr. Geoffrey Wango Counselling Psychology University of Nairobi * 11/11/2017 Future efforts in counselling and psychotherapy and other psychological services particularly in the more developing communities should focus on three major aspects, that is, (1) The neuropathological picture of psychosis...
  • Purpose: The Key To Meaningful Work and Life

    Purpose: The Key To Meaningful Work and Life

    The reason for which something exists or is accomplished. Your (or your organization's) reason for being. A way to bring meaning to your life and your work "Meaning" or "calling" It is the reason we work beyond financial rewards and...
  • Applications of GAs: TSP &amp; Sorting &amp;DiPres

    Applications of GAs: TSP & Sorting &DiPres

    in Michigan-style Classifier Systems When solving optimization problems it is desirable to replace good solutions whereas in LCS replacing a very good classifier is quite dangerous, because the system's real-time performance might drop significantly after a "few good" rules have...
  • The Sales Manager&#x27;S Behavior and Activities

    The Sales Manager'S Behavior and Activities

    In the contribution margin approach, costs are separated according to controllability. Commonly Used Cost Classifications Direct cost Indirect cost Fixed cost Variable cost Standard cost Controllable cost Uncontrollable cost TECHNIQUES OF COST ANALYSIS Direct expenses are measured and assigned to...