● Covered by 1 source · 1 reportMedium impact1 negative
Musl C library shows significant performance degradation compared to glibc, even with alternative allocators
Key points
- Musl's default allocator is significantly slower than glibc's.
- Using mimalloc with musl still results in 26% slower performance than glibc.
- Performance issues are not limited to high concurrency scenarios.
- Bifrost will remove musl as a prebuilt option due to performance concerns.
Musl's Performance Shortcomings Identified
Recent analysis indicates that the musl C library exhibits notable performance issues, particularly concerning its default memory allocator. Initial adoption of musl for projects like Bifrost was driven by its ability to create self-contained binaries, but subsequent testing revealed significant performance regressions.
Benchmarking Results Against Glibc
Measurements conducted on 4-core EC2 virtual machines demonstrated that musl's allocator is suboptimal. Even when replacing musl's default allocator with mimalloc, performance remained 26% slower compared to glibc. This performance gap was observed across various task types, including 'scan_usages' and 'structural_clone_smells', with some tasks showing proportional degradation.
Beyond the Allocator: Other Suboptimal Routines
Further investigation suggests that the performance issues in musl are not solely due to its allocator. Several common memory routines within musl are also identified as being particularly slow. This indicates a broader architectural characteristic where simplicity in musl comes at a performance cost.
Impact on Projects and Future Considerations
For performance-sensitive applications like Bifrost, the observed slowdowns are critical. Consequently, musl will be removed as a prebuilt option for Bifrost. Smaller projects where a 25% performance difference is less impactful may continue to use musl with mimalloc for its simplicity benefits.
✨ This summary was generated by AI from the outlets' reporting listed below. It is not independently verified and may contain errors — check the original sources. How BrevFeed works →
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Reporting from
Benchmarking reveals that the musl C library, even when paired with optimized allocators like mimalloc, performs substantially slower than glibc in various tasks. This performance deficit is attributed to musl's suboptimal default allocator and other common memory routines, impacting applications like Bifrost.