Yury Selivanov added the comment: tl;dr I'm attaching a new patch - fastint4 -- the fastest of them all. It incorporates Serhiy's suggestion to export long/float functions and use them. I think it's reasonable complete -- please review it, and let's get it committed.
== Benchmarks == spectral_norm (fastint_alt) -> 1.07x faster spectral_norm (fastintfloat) -> 1.08x faster spectral_norm (fastint3.patch) -> 1.29x faster spectral_norm (fastint4.patch) -> 1.16x faster spectral_norm (fastint**.patch)-> 1.31x faster nbody (fastint**.patch) -> 1.16x faster Where: - fastint3 - is my previous patch that nobody likes (it inlined a lot of logic from longobject/floatobject) - fastint4 - is the patch I'm attaching and ideally want to commit - fastint** - is a modification of fastint4. This is very interesting -- I started to profile different approaches, and found two bottlenecks, that really made Serhiy's and my other patches slower than fastint3. What I found is that PyLong_AsDouble can be significantly optimized, and PyLong_FloorDiv is super inefficient. PyLong_AsDouble can be sped up several times if we add a fastpath for 1-digit longs: // longobject.c: PyLong_AsDouble if (PyLong_CheckExact(v) && Py_ABS(Py_SIZE(v)) <= 1) { /* fast path; single digit will always fit decimal */ return (double)MEDIUM_VALUE((PyLongObject *)v); } PyLong_FloorDiv (fastint4 adds it) can be specialized for single digits, which gives it a tremendous boost. With those too optimizations, fastint4 becomes as fast as fastint3. I'll create separate issues for PyLong_AsDouble and FloorDiv. == Micro-benchmarks == Floats + ints: -m timeit -s "x=2" "x*2.2 + 2 + x*2.5 + 1.0 - x / 2.0 + (x+0.1)/(x-0.1)*2 + (x+10)*(x-30)" 2.7: 0.42 (usec) 3.5: 0.619 fastint_alt 0.619 fastintfloat: 0.52 fastint3: 0.289 fastint4: 0.51 fastint**: 0.314 === Ints: -m timeit -s "x=2" "x + 10 + x * 20 - x // 3 + x* 10 + 20 -x" 2.7: 0.151 (usec) 3.5: 0.19 fastint_alt: 0.136 fastintfloat: 0.135 fastint3: 0.135 fastint4: 0.122 fastint**: 0.122 P.S. I have another variant of fastint4 that uses fast_* functions in ceval loop, instead of a big macro. Its performance is slightly worse than with the macro. ---------- Added file: http://bugs.python.org/file41811/fastint4.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue21955> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com