Exploring trade-offs between Latency and Throughput in the Nostrum Network on Chip

• During the past years has the Nostrum Network on Chip (NoC) been developed to become a competitive platform for network based on-chip communication. The Nostrum NoC provides a versatile communication platform to connect a large number of intellectual properties (IP) on a single chip. The communication is based on a packet switched network which aims for a small physical footprint while still providing a low communication overhead. To reduce the communication network size, a queue-less network has been the research focus. This network uses de ective hot-potato routing which is implemented to perform routing decisions in a single clock cycle. Using a platform like this results in increased design reusability, validated signal integrity, and well developed test strategies, in contrast to a fully customised designs which can have a more optimal communication structure but has a significantly longer development cycle to verify the new design accordingly. Several factors are considered when designing a communication platform. The goal is to create a platform which provides low communication latency, high throughput, low power consumption, small footprint, and low design, verification, and test overhead. Proximity Congestion Awareness is one technique that serves to reduce the network load. This leads to that the latency is reduced which also increases the network throughput. Another technique is to implement low latency paths called Data Motorways achieved through a clocking method called Globally Pseudochronous Locally Synchronous clocking. Furthermore, virtual circuits can be used to provide guarantees on latency and throughput. Such guarantees are dificult in hot-potato networks since network access has to be ensured. A technique that implements virtual circuits use looped containers that are circulating on a predefined circuit. Several overlapping virtual circuits are possible by allocating the virtual circuits in different Temporally Disjoint Networks. This thesis summarise the impact the presented techniques and methods have on the characteristics on the Nostrum model. It is possible to reduce the network load by a factor of 20 which reduces the communication latency. This is done by distributing load information between the Switches in the network. Data Motorways can reduce the communication latency with up to 50% in heavily loaded networks. Such latency reduction results in freed buffer space in the Switch registers which allows the traffic rate to be increased with about 30%.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Nyckelord

Micro electronics

Nostrum

Network on Chip

NoC

on-chip networks

micro networks

Nätverk på kisel

Nätverk på chip

Other electrical engineering, electronics and photonics

Övrig elektroteknik, elektronik och fotonik

Publikations- och innehållstyp

vet (ämneskategori)

lic (ämneskategori)