Hardware-Software Trade-offs in Synchronization and Data Layout

Table of Contents

Hardware-Software Trade-offs in Synchronization and Data Layout

Role of Synchronization

Mini-Instruction Set debate

Other forms of hardware support

Components of a Synchronization Event

Strawman Lock

Atomic Instructions

Simple Test&Set Lock

Performance Criteria for Synch. Ops

T&S Lock Microbenchmark: SGI Chal.

Enhancements to Simple Lock

Improved Hardware Primitives: LL-SC

Simple Lock with LL-SC

Trade-offs So Far

Ticket Lock

Array-based Queuing Locks

Lock Performance on SGI Challenge

Point to Point Event Synchronization

Barriers

A Simple Centralized Barrier

A Working Centralized Barrier

Centralized Barrier Performance

Improved Barrier Algorithms for a Bus

Barrier Performance on SGI Challenge

Synchronization Summary

Implications for Software

Bag of Tricks for Spatial Locality

Conflict Misses in a 2-D Array Grid

Bag of Tricks (contd.)

Home Page: http://www.cs.berkeley.edu/~culler/cs258-s99/

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David E. Culler UC Berkeley CS258 Parallel Computer Architecture Lecture 5