Repository logo

Quantifying the Semantic Gap between Serial and Parallel Programming

Accepted version


Conference Object

Change log


Zhang, X 
Jones, TM 
Campanoni, S 


Automatic parallelizing compilers are often constrained in their transformations because they must conservatively respect data dependences within the program. Developers, on the other hand, often take advantage of domain-specific knowledge to apply transformations that modify data dependences but respect the application’s semantics. This creates a semantic gap between the parallelism extracted automatically by compilers and manually by developers. Although prior work has proposed programming language extensions to close this semantic gap, their relative contribution is unclear and it is uncertain whether compilers can actually achieve the same performance as manually parallelized code when using them. We quantify this semantic gap in a set of sequential and parallel programs and leverage these existing programming-language extensions to empirically measure the impact of closing it for an automatic parallelizing compiler. This lets us achieve an average speedup of 12.6× on an Intel-based 28-core machine, matching the speedup obtained by the manually parallelized code. Further, we apply these extensions to widely used sequential system tools, obtaining 7.1× speedup on the same system.



46 Information and Computing Sciences, 4612 Software Engineering

Journal Title

Proceedings - 2021 IEEE International Symposium on Workload Characterization, IISWC 2021

Conference Name

2021 IEEE International Symposium on Workload Characterization (IISWC)

Journal ISSN

Volume Title




All rights reserved
Engineering and Physical Sciences Research Council (EP/K026399/1)
Engineering and Physical Sciences Research Council (EP/P020011/1)
Is supplemented by: