Rapidgzip: Parallel Decompression and Seeking in Gzip Files Using Cache Prefetching

TL;DR

Rapidgzip introduces a parallel decompression architecture that efficiently handles arbitrary gzip files using cache prefetching, significantly outperforming traditional gzip in multi-core environments.

Contribution

It generalizes existing parallel gzip decompression methods by removing content restrictions and employing cache prefetching for reliable, high-speed decompression on arbitrary gzip data.

Findings

Achieves 8.7 GB/s decompression bandwidth with 128 cores

Provides a 55x speedup over GNU gzip on base64 data

Attains a 33x speedup on the Silesia corpus

Abstract

Gzip is a file compression format, which is ubiquitously used. Although a multitude of gzip implementations exist, only pugz can fully utilize current multi-core processor architectures for decompression. Yet, pugz cannot decompress arbitrary gzip files. It requires the decompressed stream to only contain byte values 9-126. In this work, we present a generalization of the parallelization scheme used by pugz that can be reliably applied to arbitrary gzip-compressed data without compromising performance. We show that the requirements on the file contents posed by pugz can be dropped by implementing an architecture based on a cache and a parallelized prefetcher. This architecture can safely handle faulty decompression results, which can appear when threads start decompressing in the middle of a gzip file by using trial and error. Using 128 cores, our implementation reaches 8.7 GB/s decompression bandwidth for gzip-compressed base64-encoded data, a speedup of 55 over the single-threaded GNU gzip, and 5.6 GB/s for the Silesia corpus, a speedup of 33 over GNU gzip.