230 likes | 453 Views
Lecture 3: Computer Architectures. Basic Computer Architecture. Von Neumann Architecture. Memory. instruction. data. Input unit. Output unit. ALU. Processor. CU. Reg. Levels of Parallelism. Bit level parallelism Within arithmetic logic circuits Instruction level parallelism
E N D
Basic Computer Architecture • Von Neumann Architecture Memory instruction data Input unit Output unit ALU Processor CU Reg.
Levels of Parallelism • Bit level parallelism • Within arithmetic logic circuits • Instruction level parallelism • Multiple instructions execute per clock cycle • Memory system parallelism • Overlap of memory operations with computation • Operating system parallelism • More than one processor • Multiple jobs run in parallel on SMP • Loop level • Procedure level
Levels of Parallelism Bit Level Parallelism Within arithmetic logic circuits
Levels of Parallelism Instruction Level Parallelism (ILP) Multiple instructions execute per clock cycle • Pipelining (instruction - data) • Multiple Issue (VLIW)
Levels of Parallelism Memory System Parallelism Overlap of memory operations with computation
Levels of Parallelism Operating System Parallelism • There are more than one processor • Multiple jobs run in parallel on SMP • Loop level • Procedure level
Flynn’s Taxonomy • Single Instruction stream - Single Data stream (SISD) • Single Instruction stream - Multiple Data stream (SIMD) • Multiple Instruction stream - Single Data stream (MISD) • Multiple Instruction stream - Multiple Data stream (MIMD)
Single Instruction stream - Single Data stream (SISD) • Von Neumann Architecture Memory instruction data ALU CU Processor
Flynn’s Taxonomy • Single Instruction stream - Single Data stream (SISD) • Single Instruction stream - Multiple Data stream (SIMD) • Multiple Instruction stream - Single Data stream (MISD) • Multiple Instruction stream - Multiple Data stream (MIMD)
Single Instruction stream - Multiple Data stream (SIMD) • Instructions of the program are broadcast to more than one processor • Each processor executes the same instruction synchronously, but using different data • Used for applications that operate upon arrays of data data PE data PE instruction CU Memory data PE data PE instruction
Flynn’s Taxonomy • Single Instruction stream - Single Data stream (SISD) • Single Instruction stream - Multiple Data stream (SIMD) • Multiple Instruction stream - Single Data stream (MISD) • Multiple Instruction stream - Multiple Data stream (MIMD)
Multiple Instruction stream - Multiple Data stream (MIMD) • Each processor has a separate program • An instruction stream is generated for each program on each processor • Each instruction operates upon different data
Multiple Instruction stream - Multiple Data stream (MIMD) • Shared memory • Distributed memory
Shared vs Distributed Memory • Distributed memory • Each processor has its own local memory • Message-passing is used to exchange data between processors • Shared memory • Single address space • All processes have access to the pool of shared memory P P P P Bus Memory M M M M P P P P Network
Distributed Memory • Processors cannot directly access another processor’s memory • Each node has a network interface (NI) for communication and synchronization M M M M P P P P NI NI NI NI Network
Distributed Memory • Each processor executes different instructions asynchronously, using different data instr data M CU PE data data data data data instr M CU PE Network data instr M CU PE data instr M CU PE
Shared Memory • Each processor executes different instructions asynchronously, using different data data CU PE data CU PE Memory data CU PE data CU PE instruction
P P P P P P P P Bus Bus Memory Memory Shared Memory • Uniform memory access (UMA) • Each processor has uniform access to memory (symmetric multiprocessor - SMP) • Non-uniform memory access (NUMA) • Time for memory access depends on the location of data • Local access is faster than non-local access • Easier to scale than SMPs P P P P Bus Memory Network
Distributed Shared Memory • Making the main memory of a cluster of computers look as if it is a single memory with a single address space • Shared memory programming techniques can be used
Multicore Systems • Many general purpose processors • GPU (Graphics Processor Unit) • GPGPU (General Purpose GPU) • Hybrid Memory • The trend is: • Boardcomposed ofmultiple manycorechipssharingmemory • Rack composedof multipleboards • A room full of these racks
Distributed Systems • Clusters • Individual computers, that are tightly coupled by software, in a local environment, to work together on singleproblems or on related problems • Grid • Many individual systems,that are geographicallydistributed, are tightly coupledby software,to work together on singleproblems or on related problems