LIKWID: A lightweight performance-oriented tool suite for x86 multicore environments

TL;DR

LIKWID is a lightweight command-line tool suite designed for x86 multicore systems, enabling detailed microarchitectural probing, thread affinity management, performance measurement, and hardware prefetcher control to optimize application performance.

Contribution

It introduces a comprehensive set of utilities and an API for performance analysis and optimization tailored to multicore x86 architectures, with clear distinctions from existing tools like PAPI.

Findings

Thread pinning significantly impacts performance.

Affinity and hardware counters help optimize stencil code performance.

Tools effectively analyze shared cache utilization.

Abstract

Exploiting the performance of today's processors requires intimate knowledge of the microarchitecture as well as an awareness of the ever-growing complexity in thread and cache topology. LIKWID is a set of command-line utilities that addresses four key problems: Probing the thread and cache topology of a shared-memory node, enforcing thread-core affinity on a program, measuring performance counter metrics, and toggling hardware prefetchers. An API for using the performance counting features from user code is also included. We clearly state the differences to the widely used PAPI interface. To demonstrate the capabilities of the tool set we show the influence of thread pinning on performance using the well-known OpenMP STREAM triad benchmark, and use the affinity and hardware counter tools to study the performance of a stencil code specifically optimized to utilize shared caches on multicore chips.