150 likes | 252 Views
Crossbar switches. By Alejandro Ayala. Hardware design. Show hardware design of several modern crossbar switches used for multiprocessing system on chip or multicore design. AMD Opteron Architecture [1]. Integrated N.Bridge Data & Command packets are separated. Intel Xeon 7500 [2].
E N D
Crossbar switches By Alejandro Ayala
Hardware design • Show hardware design of several modern crossbar switches used for multiprocessing system on chip or multicore design.
AMD Opteron Architecture [1] • Integrated N.Bridge • Data & Command packets are separated
Intel Xeon 7500 (cont) • 8 port (each 80bit) • Intel QuickPath Interconnect communication
UltraSPARC T2 [4] • pipeline crossbar • High-bandwidth • 8x9 xBar • Cores-Mem • Cores-I/O
UltraSparc T2 (cont) • Divided into two parts • PCX • CPX • PCX/CPX divided into two parts • Arbiter • Assigns by old age • Data slice
Characteristics of the crossbar • Compare characteristics of several switches used in modern MPSoC design • Are the switches buffered or bufferless? Is buffering done at the input, output, or at each crosspoint? What is the size of the buffers? Why that much? • How is the crosspoint implemented? Are the crossbars pipelined? What is the size of the crossbar switch? What is the bandwidth?
AMD Opteron [1] • Buffers at Input • Size are allocated to optimize throughput
System Request Queue (SRQ) • What is the System request queue in AMD64 Opteron, Athlon X2?
System Request Queue [1] • Prioritizes the access from both cores to use the crossbar. • Prevents contention to memory/resources
Knockout switch • What is knockout switch?
Knockout switch [3] • Problem: • Fully connected switch (ie every input connects to every output) • Congestion at output – different input might want to talk to same output. • Solution: • Concentrator at output • Buffer
Knockout switch Bus Interface
References [1] Pat Conway, Bill Hughes, "The AMD Opteron Northbridge Architecture," IEEE Micro, vol. 27, no. 2, pp. 10-21, Mar./Apr. 2007,doi:10.1109/MM.2007.43 [2] Intel Xeon Processor 7500 series Volume 2, Datasheet, March 2010 [3] Y. Yeh, M. Hluchyj, and A. Acampora, “The Knockout Switch: A Simple, Modular Architecture for High-Performance Packet Switching,” IEEE J. Selected Areas in Comm., vol. 5, no. 8, pp. 1274- 1287, Oct. 1987. [4] U. G. Nawathe, et al.. “An 8-Core 64 Thread 64b Power-Efficient SPARC SoC,” in IEEE International Solid-State Circuits Conference (ISSCC), Dig. Tech Papers, Feb. 2007, pp. 108-110.