Title
CORF: Coalescing Operand Register File for GPUs
Abstract
The Register File (RF) in GPUs is a critical structure that maintains the state for thousands of threads that support the GPU processing model. The RF organization substantially affects the overall performance and the energy efficiency of a GPU. For example, the frequent accesses to the RF consume a substantial amount of the dynamic energy, and port contention due to limited ports on operand collectors and register file banks affect performance as register operations are serialized. We present CORF, a compiler-assisted Coalescing Operand Register File which performs register coalescing by combining reads to multiple registers required by a single instruction, into a single physical read. To enable register coalescing, CORF utilizes register packing to co-locate narrow-width operands in the same physical register. CORF uses compiler hints to identify which register pairs are commonly accessed together. CORF saves dynamic energy by reducing the number of physical register file accesses, and improves performance by combining read operations, as well as by reducing pressure on the register file. To increase the coalescing opportunities, we re-architect the physical register file to allow coalescing reads across different physical registers that reside in mutually exclusive sub-banks; we call this design CORF++. The compiler analysis for register allocation for CORF++ becomes a form of graph coloring called the bipartite edge frustration problem. CORF++ reduces the dynamic energy of the RF by 17%, and improves IPC by 9%.
Year
DOI
Venue
2019
10.1145/3297858.3304026
Proceedings of the Twenty-Fourth International Conference on Architectural Support for Programming Languages and Operating Systems
Keywords
Field
DocType
compiler, gpu, graph coloring, microarchitecture, register coalescing, register file, register packing
Register allocation,Computer science,Efficient energy use,Parallel computing,Operand,Register file,Compiler,Thread (computing),Graph coloring,Microarchitecture
Conference
ISBN
Citations 
PageRank 
978-1-4503-6240-5
0
0.34
References 
Authors
0
5
Name
Order
Citations
PageRank
Hodjat Asghari Esfeden1202.63
Farzad Khorasani200.34
Hyeran Jeon3805.54
Daniel T. Wong465.69
Nael B. Abu-Ghazaleh51538158.15