$ show RRZE-HPC/likwid
Likwid is a comprehensive performance monitoring and benchmarking tool suite for HPC environments. It provides command-line tools (likwid-perfctr, likwid-pin, likwid-bench, likwid-powermeter, likwid-topology, etc.) and a C/Fortran/Lua library for reading hardware performance counters, managing CPU/GPU topology, controlling system features (turbo, prefetchers, RAPL power limits), and pinning threads. The architecture is modular: a core C library (liblikwid) handles low-level hardware access via MSR, PCI, MMIO, or a privileged daemon, while Lua scripts provide user-facing interfaces. External dependencies (Lua, hwloc, GOTCHA, cwisstable) are bundled. The codebase supports x86, ARM, POWER, and GPU (NVIDIA, AMD) architectures with per-architecture performance counter definitions. It is primarily an application tool, though its extensive hardware counter definitions and benchmark infrastructure also serve research purposes.
The LLM identified 5 files worth highlighting for reuse:
A header-only C implementation of Google's SwissTable hash map, with SSE2/SSSE3 optimizations for fast lookup. Provides flat and node-based variants. Reusable in any C project requiring a high-performance hash table.
A standalone infix expression evaluator using a stack-based algorithm. Supports variables, functions, and operator precedence. Can be extracted and reused in any application needing runtime expression parsing.
Implements a client for communicating with the Likwid access daemon over Unix sockets. Handles daemon startup, connection, and request/response for privileged MSR/PCI operations. The pattern is reusable for any tool requiring a privileged helper daemon.
Provides convenience functions for managing dynamic lists of bstrings (safe C strings). Includes creation, splitting, joining, and freeing. Reusable in any C project needing flexible string list manipulation.
Parses Likwid configuration from environment variables and config files with fallback logic. Supports boolean, integer, and string options. The pattern of layered configuration (env var > config file > default) is reusable in other tools.