[mingw-w64-cross-winpthreads] pthread_spin_lock() takes a lot of time

[xiaowen64]

Description / Steps to reproduce the issue

I found my code became significantly slower back in last October and VTune revealed the majority of time spent is in pthread_spin_lock(). I didn't report right away because libwinpthread.dll was changing rapidly at that time. Now I found the problem is still there. My code use boost::asio for thread pooling and a lot of context switches are expected. I understand on windows, one should never use spinlock. Could this sudden perf degradation be caused by some change of low-level threading model in libwinptghread?

Expected behavior

spinlock should not take significant time.

Actual behavior

spinlock takes 99% of the time

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-26200

Are you willing to submit a PR?

No response

[lygstate]

better a simplified demo would help a lot

[xiaowen64]

I can't easily split a simply demo. The above is a snap from vtune capture. apparently std::call_once -> _-gthread_once -> pthread_once -> pthread_spin_lock.