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• #DEPARTMENT ADLOCK TAMU HOW TO#

Carpool is based on three key ideas: it (1) adaptively forks multicast flit replicas (2) merges hotspot flits and (3) employs a novel parallel port allocation mechanism within its routers, which reduces the router critical path latency by 5.7% over a bufferless network router without multicast support. We propose Carpool, the first bufferless on-chip network optimized for one-to-many (i.e., multicast) and many-to-one (i.e., hotspot) traffic. Unfortunately, this hardware support cannot be used in bufferless on-chip networks, which are shown to have lower hardware complexity and higher energy efficiency than buffered networks, and thus are likely a good fit for large-scale CMPs. To alleviate this congestion, prior work provides hardware support for efficient one-to-many and many-to-one flows in buffered on-chip networks. As the number of cores in a CMP increases, one-to-many and many-to-one flows result in greater congestion on the network. Operations such as coherence and synchronization generate a significant amount of the on-chip network traffic, and often create network requests that have one-to-many (i.e., a core multicasting a message to several cores) or many-to-one (i.e., several cores sending the same message to a common hotspot destination core) flows. Modern chip multiprocessors (CMPs) employ on-chip networks to enable communication between the individual cores. A halo topol- ogy design additionally improves the average IPC by 18% over a mesh topology.

Specifically, Multicast Fa st- LRU replacement improves the average IPC by 20% com- pared with Multicast Promotion replacement. Simulation results show that our networked cache system improves the average IPC by 38% over the mesh network de- sign with Multicast Promotion replacement while using only 23% of the interconnection area. Finally we propose a deadlock-free XYX routing algorithm and a new halo network topology to minimize the number of links in the network.

Nex t, we present Fast-LRU replacement, where cache replacement overlaps with data request delivery. We propose a single-cycle router architecture tha t can efficiently support multicasting in on-chip caches.

#DEPARTMENT ADLOCK TAMU HOW TO#

Mo- tivated by our observations, we investigate how to optimize cache operations and design the network in large scale cache systems. Also the network delay is significantly large (63% of cache access time). We observe that net- work resources in NUCAs are underutilized and occupy con- siderable chip area (52% of cache area). Recently proposed Non-Uniform Cache Architectures (NUCAs) use wormhole-routed 2D mesh networks to improve the performance of on-chip L2 caches. Addressing these two issues is challenging because in-depth knowledges of interconnects and the specific domain are required. However, using a general on-chip network for a specific do- main may cause underutilization of the network resources and huge network delays because the interconnects are not optimized for the domain. On-chip netwo rks have been adopted to overcome scalability and the poor re- source sharing problems of shared buses or dedicated wires. As circuit integration technology advances, the design of efficient interconnects has become critical.