Parallel Architectures

Part 1:

The rise of parallel machines

Early Multicore Processors

SUN UltraSPARC T1/T2

• 8 cores • 4/8 hardware supported threads per core • 32/64 hardware supported threads

IBM Cell processor

Current Multicore Processors

Intel Core i9

Core i9-7920X: 12 cores/24 threads,16.5MB cache, 140W, 44 PCIe lanes Core i9-7900X: 10 cores/20 threads, 3.3-4.3GHz, 13.75MB cache, 140W, 44 PCIe lanes Core i9-7820X: 8 cores/16 threads, 3.6- 4.3GHz, 11MB cache, 140W, 28 PCIe lanes Core i9-7800X: 6 cores/12 threads, 3.5- 4GHz, 8.25MB cache, 140W, 28 PCIe lanes

AMD Ryzen 9

Ryzen 9 1998X: 16 cores/32 threads, 3.5-to-3.9GHz, 155W Ryzen 9 1998: 16 cores/32 threads, 3.2-to-3.6GHz, 155W Ryzen 9 1977X: 14 cores/28 threads, 3.5-to-4.1GHz, 155W Ryzen 9 1977: 14 cores/28 threads, 3.2-to-3.7GHz, 140W Ryzen 9 1976X: 12 cores/24 threads, 3.6-to-4.1GHz, 140W Ryzen 9 1956X: 12 cores/24 threads, 3.2-to-3.8GHz, 125W Ryzen 9 1956: 12 cores/24 threads, 3.0-to-3.7GHz, 125W Ryzen 9 1955X: 10 cores, 3.6-to-4.0GHz, 125W Ryzen 9 1955: 10 cores, 3.1-to-3.7GHz, 125W

GPUs

NVIDIA Titan XP

3840 NVIDIA CUDA cores running at 1.6 GHz

12 TFLOPS

12 GB of GDDR5X memory

NVIDIA GeForce GTX

GEFORCE GTX 1080 Ti: 3584 NVIDIA CUDA cores running at 1.58 GHz. 11 GB of GDDR5X memory.

GEFORCE GTX 1080: 2560 NVIDIA CUDA cores running at 1.6 GHz. 8 GB of GDDR5X memory.

...

GEFORCE GTX 950: 768 NVIDIA CUDA cores running at 1 GHz. 2 GB of GDDR5X memory.

Lab Custer for Research Software Dev.

Eight Intel Quad Core processor @ 1.6GHz with 8 GB DDR2 RAM

Part 2:

Taxonomies for Parallel Architectures

Taxonomies for Parallel Architectures • Floyd’s Taxonomy - program control and memory access • Taxonomy Based on Memory Organization • Taxonomy Based on Processor Granularity • Taxonomy Based on Processor Synchronization • Taxonomy Based on Interconnection Architecture

Floyd’s Taxonomy

• Computer architectures: – SISD – MISD – SIMD – MIMD • Based on method of program control and memory access

SISD Computers

• Standard sequential computer. • A single processing unit receives a single stream of instructions that operate on a single stream of data.

MISD Computers

• p processors, each with its own control unit, share a common memory.

SIMD Computers

• All p identical processors operate under the control of a single instruction stream issued by a central control unit. • There are p data streams, one per processor so different data can be used in each processor.

MIMD Computers

• p processors • p streams of instructions • p streams of data

Taxonomy Based on Memory Organization • Distributed memory • Shared memory – UMA – NUMA

• Each processor has its own memory • Communication is usually performed by message passing • Each processor can access – its own memory, directly – memory of another processor, via message passing

Interconnect

Shared Memory

• provides hardware support for read/write to a shared memory space • has a single address space shared by all processors

I/O devices

Mem Mem Mem Mem I/O ctrl I/O ctrl

Interconnect Interconnect

Processor Processor

Scaling Up…

– Problem is interconnect: cost (crossbar) or bandwidth (bus) – Dance-hall: bandwidth still scalable, but lower cost than crossbar • latencies to memory uniform, but uniformly large – Distributed memory or non-uniform memory access (NUMA) • Construct shared address space out of simple message transactions across a general-purpose network (e.g. read-request, read-response) – Caching shared (particularly nonlocal) data?

Taxonomy Based on Processor Granularity

• Coarse Grained: Few powerful processors • Fined Grained: Many small processors (massively parallel) • Medium Grained: …between the two...

Taxonomy Based on Processor Synchronization

• Asynchronous: Processors run on independent clocks. User has synchronize via message passing or shared variable. • Fully Synchronous: Processors run in sync on one global clock. • Bulk-synchronous: Hybrid. Processors have independent clocks. Support is provided for global synchronization to be called by the user’s application program.

Taxonomy Based on Interconnection Architectures

• Static – Point to point connections

• Dynamic – Network with switches – Crossbars – Buses Interconnect Network

Static Interconnection Topologies

Linear Array

Ring

• Diameter (Max distance between processors) • Bisection Width (Min cuts to break into equal halves) • Cost (number of links)

Static Interconnection Topologies

Mesh Torus

Diameter? Bisection Width ? Cost ? Static Interconnection Topologies • Tree

Diameter? Bisection Width ? Cost ?

Static Interconnection Topologies • Complete Network

Diameter? Bisection Width ? Cost ?

Static Interconnection Topologies • d-dim Hypercube

d 2 processors d=4 d=0 d=1 d=2 d=5

d=3

Diameter? Bisection Width ? Cost ? Static Interconnection Topologies • Fat Tree

Diameter? Bisection Width ? Cost ?

Switch based interconnection network

Summary

Taxanomy of parallel machines

Fine grained

Coarse grained massively parallel coarse clusters Distributed grained memory clusters

GPU Shared multi-core memory

MIMD SIMD

• Massively parallel cluster (MIMD, distributed memory, fine grained) • Coarse grained cluster (MIMD, distributed memory, coarse grained) • Multi-core processor (MIMD, shared memory, coarse grained)

• GPU (SIMD, shared memory, fine grained)