luhenry
commented
3 years ago I've noticed in the past that f2j blas was pretty suboptimal, especially with regards to making hotspot happy. Looks like you did most of what I was able to figure out (and a bunch of stuff I didn't I'm sure).
One thing I had noticed previously was that extracting methods for the various branches (e.g. incx == 1 vs != 1) would frequently make the inliner happier, especially in "real use" since it wouldn't hit method size limits.
Yes, a bunch of the speedup comes from clearly outlining loop unrolling that hotspot can easily vectorize. A big limitation of Hotspot nowadays is that it's unable to vectorize for (...) { sum += a[i] * b[i] }. It will vectorize the a[i] * b[i] but it won't vectorized the sum += ... with for (...) { sum0 += a[i+0] * b[i+0]; sum1 += a[i+1] * b[i+1]; } sum += sum0 + sum1; This patterns is what allows to get such a huge boost with JDK16 when using the Vector API.
I'll need to update docs etc too. Looks like we can basically just delete the natives project?
Short answer yes. However, removing the whole project implies that it would break any project depending on it. Keeping it would allow not to break them, even though it would be empty and thus dead weight. I'll leave that to you to decide, just let me know.
dlwh
Following https://github.com/apache/spark/pull/32415, I would like to update Breeze to take advantage of
dev.ludovic.netlibin place ofcom.github.fommil.netlib.This package provides faster pure-java fallback on Java 8, 11, and 16+, and provides a JNI-based wrapper that doesn't rely on any GPL or LGPL libraries.
The performance numbers on Spark are the following:
JDK8:
JDK11:
JDK16: