Corse Overview Miodrag Bolic ELG 7187 Topics in

Corse Overview Miodrag Bolic ELG 7187 Topics in Computers: Multiprocessor Systems on Chip

Topics covered • • • Performance metrics Interconnection networks Cache coherence Synchronization and memory consistency Multithreading

Performance metrics • • • Speedup Amhdal’s law Gustafdon’s law Scalable computing Benchmarks Performance counters and their implementation

Interconnection networks • Interconnection topologies – Definition of degree, diameter, bandwidth, channel load, traffic pattern – Different topologies – Multicore topics: topology customization, iregular topologies, concentration

Interconnection networks • Routing – Deterministic, adaptive, oblivious • Flow control – – Switching and packet networks Store and forward, virtual cut through, wormhole Virtual channels Flow control • Credit based • On-off control

Interconnection networks • Router micro-architecture – – – Architecture of the router Router pipeline Lookahead routing and bypassing Buffer organization Crossbar implementation Arbiters and allocators

Cache coherence • Snooping algorithms – MSI, MESI – Reading • Implementation of snooping protocols – Organization of the cache controller – Cache controller for split-transaction buses

Cache coherence • Directory-based cache coherence – Types of directories • Directory implementation in multicores – MSI directory protocol – Coherence Bandwidth Requirements – Issues with private and shared L 2 caches

Synchronization • Implementation of locks • Implementation of barrier • Problems including serialization, deadlock, livelock and starvation • Implementation of locks and barriers for distributed memory systems • Transactional memory – Software and hardware transactional memory – Jonathan’s scribing and report

Memory consistency models • • Models Sequential Consistency Relaxed Memory Models Eager and lazy implementations of relaxed consistency

Applications – embedded multicores • Hardware Perspective – Example of Freescale Qor. IQ – Example implementation of an router • Software perspective – Symmetric and asymmetric processing – Hypervisor and virtual machines

Applications: Server Architectures 1. What makes a server CPU different ? 2. Different type of architectures 3. Bulldozer Microarchitecture § Bulldozer vs. Westmere’s architecture § Example of Interlagos

Applications: Cloud computing • Definition of the cloud • Why cloud computing • Example of the Amazon cloud

Multithreading • • Fine-grained Coarse grained Simultaneous Speculative