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?

この issue ではファイルではなく、DO_FCALL と ZEND_VM_FCALL_INTERRUPT_CHECK が挙げられています。まず、VM が内部呼び出しに対する割り込みチェックをどこで実行しているのか、また高速な拡張関数がどのように表現されているのかを追跡してください。完了とするには、レビュー済みのエンジンレベルのアプローチに加え、割り込みの挙動を弱めることなくオーバーヘッドが削減されていることを示すベンチマークの証拠が必要です。