Performance penalty for builtin/extension functions due to interrupt checks

Description

I was profiling an extension that's intended to act as a faster replacement for the pack() and unpack() functions. The functions in the extension are very fast - just a few instructions each.

During profiling I discovered, much to my surprise, that the overhead of the DO_FCALL opcode far exceeded the time actually spent in my function, and that 2/3rds of the overhead was coming from ZEND_VM_FCALL_INTERRUPT_CHECK.

Doing some digging I found that this interrupt check runs after every single internal function call. This means that my extension's functions are being overshadowed by interrupt checks on every call which are >5x slower than the actual function itself.

The net result overall is less visible (a 5-10% performance degradation in my synthetic test script), but I have to ask if there's a better way to do this. Why is PHP checking for interrupts after every internal function call? I get it for stuff like network and I/O functions which could take a long time, but not every builtin function is like that. For the fast ones, this is an unavoidable and (probably) unnecessary performance penalty.

I don't know much about how the interrupt system works, but my feeling is that there has to be a better way to implement it than having every internal function call pay such a penalty. Even if there was a way to avoid this interrupt check with some ZEND_ACC flag that would tell the engine a function is "fast" and not to do the interrupt check?

Issue này nêu DO_FCALL và ZEND_VM_FCALL_INTERRUPT_CHECK thay vì một tệp. Hãy bắt đầu bằng cách lần theo nơi VM thực hiện việc kiểm tra ngắt đối với các lệnh gọi nội bộ và cách các hàm extension nhanh được biểu diễn. Công việc sẽ được xem là hoàn tất khi có một phương án ở cấp engine đã được review, cùng với bằng chứng benchmark cho thấy overhead được giảm mà không làm suy yếu hành vi ngắt.