← Sunday, September 27, 2026Performance & OSDeep dive
Loongson atomic-add failure caused a lost update in OpenMP code
An OpenMP atomic accumulation on a Loongson server occasionally produced a value below the expected total, and an AI-assisted investigation helped create a stable reproducer. The failure highlights how difficult CPU-level concurrency bugs can be to isolate and validate.
- What
- A LoongArch server’s normaliz package test stalled in an infinite loop while OpenMP code accumulated a shared value.
- How
- Investigation found that the CPU’s atomic-add instruction occasionally failed to be atomic; test firmware resolved the issue.
- Why it matters
- The erratum shows how a hardware atomicity fault can break concurrent software, and how firmware can address it.
Read on jia.je → Hacker News · 6 commentsLobsters
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