Lecture 9 - Åbo Akademi
Lecture 9 - Åbo Akademi Lecture 9 - Åbo Akademi
Routing algorithms • Routing algorithm must ensure freedom from livelocks • livelocks are similar to deadlocks, except that states of the resources involved constantly change with regard to one another, without making any progress • occurs especially when dynamic (adaptive) routing is used • e.g. can occur in a deflective “hot potato” routing if a packet is bounced around over and over again between routers and never reaches its destination • livelocks can be avoided with simple priority rules • Routing algorithm must ensure freedom from starvation • under scenarios where certain packets are prioritized during routing, some of the low priority packets never reach their intended destination • can be avoided by using a fair routing algorithm, or reserving some bandwidth for low priority data packets
Flow control schemes • Goal of flow control is to allocate network resources for packets traversing a NoC • can also be viewed as a problem of resolving contention during packet traversal • At the data link-layer level, when transmission errors occur, recovery from the error depends on the support provided by the flow control mechanism • e.g. if a corrupted packet needs to be retransmitted, flow of packets from the sender must be stopped, and request signaling must be performed to reallocate buffer and bandwidth resources • Most flow control techniques can manage link congestion • But not all schemes can (by themselves) reallocate all the resources required for retransmission when errors occur • either error correction or a scheme to handle reliable transfers must be implemented at a higher layer
- Page 1 and 2: Special Course in Computer Science:
- Page 3 and 4: Network-on-Chip (NoC) Why NoC OCP S
- Page 5 and 6: From simpler to more complex chips
- Page 7 and 8: Problems to solve • Cores that pe
- Page 9 and 10: Some driving forces • Technical I
- Page 11: NoC illustration
- Page 14 and 15: OCP standard for on-chip communicat
- Page 16 and 17: OCP Characteristics • IP Core •
- Page 18 and 19: Flexibility of OCP • Several usef
- Page 20 and 21: Some fundamental OCP concepts: Addr
- Page 22 and 23: Some fundamental OCP concepts: In-b
- Page 24 and 25: Some fundamental OCP concepts: Side
- Page 26 and 27: Introduction • Network-on-chip (N
- Page 28 and 29: Introduction • ISO/OSI network pr
- Page 30 and 31: NoC Topology • Most direct networ
- Page 32 and 33: NoC Topology • Folding torus topo
- Page 34 and 35: NoC Topology • Indirect Topologie
- Page 36 and 37: NoC Topology • (m, n, r) symmetri
- Page 38 and 39: NoC Topology • Irregular or ad ho
- Page 40 and 41: Switching strategies • Two main m
- Page 42 and 43: Switching strategies • Allocating
- Page 44 and 45: Switching strategies • VCT (virtu
- Page 46 and 47: Routing algorithms • Static and d
- Page 48 and 49: Routing algorithms • Minimal and
- Page 52 and 53: ACK/NACK flow control scheme • wh
- Page 54 and 55: Clocking schemes • Fully synchron
- Page 56 and 57: NoC Architectures examples
- Page 58 and 59: HERMES • Developed at the Faculda
- Page 60 and 61: Nostrum • Developed at KTH in Sto
- Page 62 and 63: QNoC • Developed at Technion in I
- Page 64 and 65: SPIN • Scalable programmable inte
- Page 66 and 67: Emerging NoC paradigms Overall goal
- Page 68 and 69: Novel Interconnect Paradigms for Mu
- Page 70 and 71: Motivation • Increasingly harder
- Page 72 and 73: Emerging Alternatives • Optical I
- Page 74 and 75: Optical Interconnects • Board-to-
- Page 76 and 77: Optical Interconnects • Waveguide
- Page 78 and 79: Optical Interconnects • OIs have
- Page 80 and 81: Optical Interconnects: Open Problem
- Page 82 and 83: RF/Wireless Interconnects • Micro
- Page 84 and 85: RF/Wireless Interconnects • Paths
- Page 86 and 87: RF/Wireless Interconnects: Open Pro
- Page 88 and 89: CNT Interconnects • Carbon nanotu
- Page 90 and 91: Multi-Wall Carbon Nanotubes (MWCNT)
- Page 94 and 95: Conceptual transmitter and receiver
- Page 98 and 99: 3D and NoCs • 3D stacking technol
Flow control schemes<br />
• Goal of flow control is to allocate network resources for<br />
packets traversing a NoC<br />
• can also be viewed as a problem of resolving contention during packet<br />
traversal<br />
• At the data link-layer level, when transmission errors occur,<br />
recovery from the error depends on the support provided by<br />
the flow control mechanism<br />
• e.g. if a corrupted packet needs to be retransmitted, flow of packets from the<br />
sender must be stopped, and request signaling must be performed to reallocate<br />
buffer and bandwidth resources<br />
• Most flow control techniques can manage link congestion<br />
• But not all schemes can (by themselves) reallocate all the<br />
resources required for retransmission when errors occur<br />
• either error correction or a scheme to handle reliable transfers must be<br />
implemented at a higher layer
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