Easy dynamic dispatch using GLIBC Hardware Capabilities
10 months ago
- #GLIBC
- #optimization
- #dynamic-dispatch
- GLIBC Hardware Capabilities (hwcaps) introduced in GLIBC 2.33+ allow dynamic dispatch by loading the highest supported CPU optimization level.
- Shared libraries can be built multiple times targeting different optimization levels (e.g., x86-64-v4, x86-64-v3, x86-64-v2) and placed in corresponding subdirectories.
- The dynamic linker/loader selects the best version based on the CPU's capabilities, falling back to lower levels if necessary.
- This method is useful for performance optimization across different architectures, as seen in the Debian packaging of ggml for llama.cpp and whisper.cpp.
- The lowest-level library (x86-64-v1) is placed in the standard path to ensure compatibility on non-GLIBC systems or when hwcaps are unavailable.
- This approach also works with RUNPATH or LD_LIBRARY_PATH, making it flexible for various deployment scenarios.