7.4 Routing Advances for Fault-tolerant and Multicast NoCs
Date: Wednesday 11 March 2015
Time: 14:30 - 16:00
Location / Room: Chartreuse
Chair:
Fabien Clermidy, CEA, FR
Co-Chair:
Masoud Daneshtalab, University of Turku, FI
NoCs are migrating into large-scale multicore systems which lead to new issues to be solved. In this session, we see how NoCs can tackle both faulty behaviors and performance bottlenecks. The first paper demonstrates low overhead multicast using surface-wave communication. The two other papers deal with low-overhead and low-latency fault-tolerance.
| Time | Label | Presentation Title Authors |
|---|---|---|
| 14:30 | 7.4.1 | MIXED WIRE AND SURFACE-WAVE COMMUNICATION FABRICS FOR DECENTRALIZED ON-CHIP MULTICASTING Speakers: Ammar Karkar1, Kin-Fai Tong2, Terrence Mak3 and Alex Yakovlev1 1School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne, GB; 2Department of Electrical and Electronic Engineering, UCL, London, GB; 3Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong, CN Abstract Network-on-chip (NoC) has emerged to tackle different on-chip challenges and has satisfied different demands in terms of high performance, economical and reliable interconnect implementation. However, a merely metal-based interconnect reaches performance bound with the relentless technology scaling. Especially, it displayed a bottleneck to meet the communication bandwidth demand for multicasting. This paper proposes a novel hybrid architecture, which improves the on-chip communication bandwidth significantly using mixed wires and surface wave interconnects (SWI) fabrics. In particular, the bandwidth of multicasting can be drastically improved. We introduce a decentralized arbitration method to fully utilize the slack-time scheduling with deadlock-free flow control. Evaluation results, based on a cycle-accurate and hardware-based simulation, demonstrate the effectiveness of the proposed architecture and methods. Compared to a wire-based NoC, the mixed fabric approach can achieve an improvement in power reduction and communication speed up to 63% and 12X, respectively. These results are achieved with almost negligible hardware overheads. This new paradigm efficiently addresses the emerged challenges for on-chip communications. Download Paper (PDF; Only available from the DATE venue WiFi) |
| 15:00 | 7.4.2 | D2-LBDR: DISTANCE-DRIVEN ROUTING TO HANDLE PERMANENT FAILURES IN 2D MESH NOCS Speakers: Rimpy Bisnhoi1, Manoj Gaur1, Vijay Laxmi1 and Josè Flich2 1Malaviya National Institute of Technology, IN; 2Associate Professor, Universitat Politècnica de València, ES Abstract With the advent of deep sub-micron technology, fault-tolerant solutions are needed to keep many-core chips operative. In NoCs, Logic Based Distributed Routing (LBDR) proved to be a flexible routing framework for 2D meshes with link and router faults. However, to provide full coverage, LBDR requires a module named FORKS which replicates some messages. This imposes the use of virtual cut-through switching and a complex router arbiter, increasing excessively the router cost, mainly in buffer area. Also, some failure combinations require the use of a non-trivial dynamic reconfiguration strategy to avoid deadlocks. We propose d2 -LBDR which adds, on every router, a distance register to the closest failure. This enables the support of more failure combinations without an excessive implementation cost. Indeed, we restore the use of wormhole switching, keeping router architecture simple, while achieving the same fault coverage as the best LBDR version, without requiring complex switching strategies nor any dynamic reconfiguration strategy. Results show that a small area overhead (3%) is enough for the implementation of a fully flexible routing method without any limiting support case when compared with LBDR. d2 -LBDR reduces area overhead over the best LBDR approach (300% overhead against 3%) while preserving fault coverage. Results show d2 -LBDR performance equal to LBDR. Download Paper (PDF; Only available from the DATE venue WiFi) |
| 15:30 | 7.4.3 | SYNERGISTIC USE OF MULTIPLE ON-CHIP NETWORKS FOR ULTRA-LOW LATENCY AND SCALABLE DISTRIBUTED ROUTING RECONFIGURATION Speakers: Marco Balboni1, Josè Flich2 and Davide Bertozzi1 1University of Ferrara, IT; 2Associate Professor, Universitat Politècnica de València, ES Abstract Abstract—Extending the principle of partially good die allowance to manycore processors, and testing them over time to detect the onset of permanent faults, are only feasible through proper support in the on-chip interconnection network. In fact, this implies the ability to reconfigure the routing algorithm at runtime to reflect changes in network topologies. Current literature cannot avoid a large hardware and/or software overhead when tackling this challenge. This paper exploits the existence of multiple physical networks in industry-relevant manycore processors in a synergistic way, for the sake of fast and scalable distributed reconfiguration of the routing function at runtime. Download Paper (PDF; Only available from the DATE venue WiFi) |
| 16:00 | IP3-10, 944 | A HYBRID PACKET/CIRCUIT-SWITCHED ROUTER TO ACCELERATE MEMORY ACCESS IN NOC-BASED CHIP MULTIPROCESSORS Speakers: Yassin Mazloumi and Mehdi Modarressi, University of Tehran, IR Abstract Modern chip multiprocessors will feature a large shared last-level cache (LLC) that is decomposed into smaller slices and physically distributed throughout the chip area. These architectures rely on a network-on-chip (NoC) to handle remote cache access and hence, NoCs play a critical role in optimizing memory access latency and power consumption. Circuit-switching is the most power- and performance-efficient switching mechanism in NoCs, but is not advantageous when the packet transmission time is not long enough compared to the circuit setup time. In this paper, we propose a zero-latency circuit setup scheme to make circuit-switching applicable in transferring individual data packets. The design leverages the fact that in CMPs with distributed LLC (where a considerable portion of the on-chip traffic is composed of remote LLC access requests and data responses), every response packet is sent in reply to a request packet and traverses the same path as its corresponding request, but at the backward direction. The short request packets, then, are responsible to reserve a path for their corresponding response packets. This NoC tries to reduce conflict among circuit paths by considering conflicts in backward direction during request packet routing, backed by a run-time technique to resolve conflicts when circuits are actually set up. Experimental results show that the proposed NoC architecture considerably reduces average packet latency that directly translates to faster memory access Download Paper (PDF; Only available from the DATE venue WiFi) |
| 16:00 | End of session Coffee Break in Exhibition Area Coffee Break in Exhibition AreaOn all conference days (Tuesday to Thursday), coffee and tea will be served during the coffee breaks at the below-mentioned times in the exhibition area. Lunch BreakOn Tuesday and Wednesday, lunch boxes will be served in front of the session room Salle Oisans and in the exhibition area for fully registered delegates (a voucher will be given upon registration on-site). On Thursday, lunch will be served in Room Les Ecrins (for fully registered conference delegates only). Tuesday, March 10, 2015Coffee Break 10:30 - 11:30 Lunch Break 13:00 - 14:30; Keynote session from 13:20 - 14:20 (Room Oisans) sponsored by Mentor Graphics Coffee Break 16:00 - 17:00 Wednesday, March 11, 2015Coffee Break 10:00 - 11:00 Lunch Break 12:30 - 14:30, Keynote lectures from 12:50 - 14:20 (Room Oisans) Coffee Break 16:00 - 17:00 Thursday, March 12, 2015Coffee Break 10:00 - 11:00 Lunch Break 12:30 - 14:00, Keynote lecture from 13:20 - 13:50 Coffee Break 15:30 - 16:00 |
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