chacha20: widen NEON bulk path to 8 parallel blocks#564
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tarcieri merged 1 commit intoRustCrypto:masterfrom May 5, 2026
Merged
chacha20: widen NEON bulk path to 8 parallel blocks#564tarcieri merged 1 commit intoRustCrypto:masterfrom
tarcieri merged 1 commit intoRustCrypto:masterfrom
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Confirmed these speedups on a M1 Max. Mine weren't quite as good, more in the realm of a 30% improvement, but still it seems worth it.
Edit: funny, because @waamm says "On an Apple M4 Max, this gives ~30% higher throughput" but the image shows 40%+?
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OpenSSL’s AArch64 ChaCha assembly uses an 8-block outer loop on its large-buffer path (see
ChaCha20_512_neonin chacha-armv8.pl), whereas this crate previously used four parallel blocks.On an Apple M4 Max, this gives
30%~45% higher throughput on bulkapply_keystream: