Repository navigation
[PERF] Construction of known cdef classes can go through __new__ #1643
Description
In driver, runtime and nvrtc, when an instance of a cdef class is contructed (usually as a return value), it just uses the obvious Python-level constructor, for example:
cdef CUtensorMap tensorMap = CUtensorMap()
This makes a slow Python-like call (the ironically named PyObject_FastCall).
Instead, following Cythons fast instantiation advice, we can use __new__, which will make a faster C-level call to __cinit__.
cdef CUtensorMap tensorMap = CUtensorMap.__new__(CUtensorMap)
Activity
mdboom commentedon Feb 18, 2026
This worked for the first class I tried (
CUtensorMap), because it has an empty__init__. For classes with things in__init__we have to move that content to__cinit__and hope that that doesn't cause subtle changes in behavior. Punting for now, since this doesn't seem as "low hanging" as I initially thought.