Due to high design and test costs for real many-core chips, simulators which allow exploring the best design options for a system before actually building it have been becoming highly necessary in system design and optimization flows.
Packets are routed on the network of routers by a selected routing algorithm to their destinations at which the packets are immediately consumed.
The proposed bypass router has above pipeline manner and also bypass action that in some cases send flits in less than three-stages.
All communications are carried out in the form of packets, subdivided into flits, which are sent through the NoC using wormhole flow control.
In this paper, we present a radically improved and extended version of Noxim, whose main novelty is the capability of simulating heterogeneous wired/wireless NoC architectures.
This choice is motivated by the fundamental requirements behind the Noxim project: allowing extensibility easiness and scalable performances while still supporting a cycle-accurate simulation.
To face with the aforementioned problems, wireless on-chip communication mechanisms recently emerged as technological alternatives to the metal/dielectric system.
- However, previous NoC designs are not scalable in terms of network latency when the communicating cores are not nearby each other.
- Another alternative is the use of the third dimension that can result in significant reduction in power and average latency of traffic in Networks-on-Chip.
In addition to providing EoS, the proposed arbitration has additional benefits which include providing quality-of-service features (such as differentiated service 区分式服务) and providing fairness in terms of both throughput and latency that approaches the global fairness achieved with age-base arbitration – thus, providing a more stable network by achieving high sustained throughput beyond saturation.
However, all arbitration algorithms mentioned above cannot well handle bandwidth and hard real-time requirements concurrently.
Network-on-chip (NoC) supports the design of the next generation multi-core chips, resulting in tremendous improvements in performance, power and reliability.
The main challenges nowadays are solving the packet latency and decreasing the power consumption, mostly produced by routers and links.
As opposed to the header flit, body and tail flits do not need to go through SA and inherit the VC allocated by the header. The tail flit releases the VC on leaving the router.
The arbitration mechanism, which is proposed in this paper, is for reducing the communication latency.
- The winner will be granted the requested port and the loser will have to wait, and be blocked thereby. Also, different information flows may have different priorities.
This is because when the output ports are allocated to the main traffic flows that have most requests, the network delay is thereby decreased and energy consumption is decreased as well.
In this case, an incoming flit enters the router, places requests for the output port determined by its preset route, and moves to the crossbar upon successful arbitration.
A high on-chip latency not just delays requests and responses, but also slows down the injection of other requests and responses (due to dependencies), leading to poorer throughput and overall system slowdown.
We reduce the effective number of hops to (H/HPC), without adding any additional physical wires in the data-path or reducing b like the high-radix router solutions do.
Plethora of research in NoCs over the past decade coupled with technology scaling has allowed the actions within a router to move from serial execution to parallel execution, via lookahead routing [11], simplified VC selection [26], speculative switch arbitration [31, 30], non-speculative switch arbitration via lookaheads [24, 27, 32, 23, 25] to bypass buffering and so on.
SMART removes this constraint of latching signals at every hop.
As technology nodes shrink, and high-end cores get augmented with smaller dedicated accelerator IPs, the size of IP blocks is expected to go down.Thus, the same wire delay- which does not scale down with technology - can translate to higher HPC_max, making SMART even more attractive.
We consider a system with one server in which the customers have preferential treatment based on priorities associated with them.
- One problem with fast arbitration schemes, such as a fixed-priority arbiter, is that fast arbitration schemes are not always fair because preference may be given to higher priority requesters.
- Another problem with such fast arbitration Schemes is that they may cause starvation because a requestor with a lower priority may never be granted use of the shared resource.
However, even with perfect routing and flow control, situations remain in which the requests for a particular resource will exceed its capacity.
In this regime, our attention shifts from efficiently allocating the resource to fairly allocating the resource according to some service policies.
Figure 1 shows a situation in which the packet advances through the pipeline stages without any stalls.
The RC and VA stages perform computation for the head flit only (once per packet). Body flits pass through these control stages with no computation.
The SA and ST stages operate on every flit of the packet. In the absence of stalls, each flit of the packet enters the pipeline one cycle behind the preceding flit and proceeds through the stages one per cycle.
The width of all channels and router pipelines always corresponds to the width of a single flit.
Despite the flexibility of the original BookSim, it did not support some of the more advanced features and topologies proposed in the context of on-chip networks.