facebook/zstd

IBM Linux on z SIMD optimization

Open

#2,679 opened on May 21, 2021

View on GitHub
 (7 comments) (4 reactions) (0 assignees)C (27,100 stars) (2,481 forks)batch import
Announcehelp wanted

Description

Is your feature request related to a problem? Please describe. IBM z architecture provides SIMD capabilities that can be utilized for zstd optimization similar to SSE and Neon SIMD optimizations that have been contributrd to zstd.

Describe the solution you'd like Optimize zstd to utilize IBMz VX SIMD intrinsics in zstd_lazy.c and ztsd_compress.c equivalent to optimization for SSE and Neon.

Describe alternatives you've considered Because zstd has implemented architecture-specific optimizations for other architectures, a hand-coded implementation has been shown to provide unique benefits above auto-vectorization.

Additional context Financial bounty from IBM available for negotiation. Inquiries from interested developers welcome.

Contributor guide

Tech stack
c
Domain
performance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
C programmingSIMD intrinsics knowledgeIBM z architecture understandingzstd codebase familiarity
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
The issue requests implementing IBM z VX SIMD intrinsics optimizations in zstd lazy.c and zstd compress.c, similar to existing SSE and Neon implementations. The contributor should study the existing SSE and Neon code paths, refer to IBM z architecture documentation for VX intrinsics, and propose a design. Maintainer feedback on scope and acceptance criteria is needed.