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Power-Aware and BIST-Aware NoC Reuse on the Testing of Core-based Systems. Érika Cota Luigi Carro Flávio Wagner Marcelo Lubaszewski UFRGS Porto Alegre, Brazil. Context. SoC. core. core. core. core. core. core. Reuse Model. tester. SoC. core. core. core. core.
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Power-Aware and BIST-Aware NoC Reuse on the Testing of Core-based Systems Érika Cota Luigi Carro Flávio Wagner Marcelo Lubaszewski UFRGS Porto Alegre, Brazil
Context SoC core core core core core core
Reuse Model tester SoC core core core core core core
Reuse Model tester SoC core core core core core core
Reuse Model tester SoC core core core core core core
Revisão dos principais objetivose fatores de sucesso Goal Improve the reuse the on-chip network as test access mechanism • minimal area overhead • zero pin overhead • feasible test time Power consumption is an issue? Optimal set of BISTed cores?
Revisão dos principais objetivose fatores de sucesso Outline • NoC-based Test • Power consumption calculation • Modified scheduling • Considering BISTed cores • Experimental Results • Final Remarks
Access Paths Within the NoC input CUT 1 input CUT 2 output output
CUT CUT CUT 2 Access Paths Within the NoC input CUT 1
CUT CUT Access Paths Within the NoC CUT 1 input CUT 2
CUT CUT CUT 2 Access Paths Within the NoC CUT 1 output
CUT CUT Access Paths Within the NoC CUT 1 CUT 2 output
CUT CUT Access Paths Within the NoC input CUT 1 CUT 2
CUT CUT Access Paths Within the NoC input CUT 1 CUT 2
CUT CUT Access Paths Within the NoC CUT 1 CUT 2 output
CUT CUT Access Paths Within the NoC CUT 1 CUT 2 output
Parallelism Within the NoC input input CUT 1 CUT 2 output output
Pipeline Within the NoC input input CUT 1 CUT 2 output CUT 3 output
Pipeline Within the NoC input input CUT 1 CUT 2 output CUT 3 output
Pipeline Within the NoC input input CUT 1 CUT 2 output CUT 3 output
Pipeline Within the NoC BOTTLENECKS! input CUT 1 CUT 2 CUT 3 output
Packets Scheduling input CUT 1 CUT 2 output CUT 3
Packets Scheduling input CUT 1 CUT 2 output CUT 3
Packets Scheduling input CUT 1 CUT 2 output CUT 3
Packets Scheduling input CUT 1 CUT 2 output CUT 3
Packets Scheduling input CUT 1 CUT 2 output CUT 3
Reuse Algorithm Define test packets Define access paths for each core Select a packet Find available access path Schedule packet
wrapper wrapper wrapper wrapper Power Consumption Calculation Core 1 Core 2 Core 3 wrapper wrapper Router Router Router Core 4 Core 5 Core 6 Router Router Router
wrapper wrapper wrapper wrapper Power Consumption Calculation Core 1 Core 2 Core 3 wrapper wrapper Router Router Router Core 4 Core 5 Core 6 Router Router Router
wrapper wrapper wrapper wrapper Power Consumption Calculation • F(#ffs, #gates, switching rate) • per cycle (any frequency) • per packet Core 1 Core 2 Core 3 wrapper wrapper Router Router Router Core 4 Core 5 Core 6 Router Router Router
wrapper wrapper wrapper wrapper Power Consumption Calculation • F(length,width,switching rate) • per cycle (any frequency) Core 1 Core 2 Core 3 wrapper wrapper Router Router Router Core 4 Core 5 Core 6 Router Router Router
wrapper wrapper wrapper wrapper Power Consumption Calculation • F(#ffs, #gates, switching rate) • per cycle (any frequency) • per pattern Core 1 Core 2 Core 3 wrapper wrapper Router Router Router Core 4 Core 5 Core 6 Router Router Router
CUT Power Consumption of One Packet input CUT 1 CUT 4*PW(router) + 3*PW(channel) + PW(CUT+wrapper)
Experimental Setup • SOCIN Network • under development at UFRGS • Grid topology • 32-bit channels • deterministic routing (XY) • ITC’02 SoC Test Benchmarks • d695, g1023 • Placement for synthetic applications
Experimental Results - d695 Cores consumption >> wrapper consumption Test time Power Limit
Experimental Results - g1023 Cores consumption >> wrapper consumption
Experimental Results - d695 Cores consumption wrapper consumption Test time Power Limit
Experimental Results - g1023 Cores consumption wrapper consumption
BIST-Aware Scheduling • Each core has a BISTed version • 30% more area • 50% more power consumption • 2x the number of test vectors • All cores BISTed • system test time = largest test time among cores • power consumption may be na issue
BIST-Aware Scheduling 1) All cores BISTed • maximum parallelization • minimum test time? 2) Define test scheduling considering power constraints 3) Replace the core with largest test time by its external tested version 4) Repeat 2 and 3 until test time increases
Experimental Results - p22810 No power constraints BISTed Cores
Experimental Results - p22810 No power constraints BISTed Cores
Experimental Results - p22810 No power constraints BISTed Cores
Experimental Results - p22810 Multiple BIST model BISTed Cores
Final Remarks • Alternative TAM for NoC-based SoCs • good trade-off test time x area X pin overhead even under power constraints (ETW’03) • Selection of the optimal set of BISTed cores for test time minimization (TRP’03) • Further selection of the best BIST method for the cores in the system