xorsimd

README

XOR SIMD

Introduction:

• XOR code engine in pure Go.

• High Performance: More than 270GB/s per physics core.

Performance

Performance depends mainly on:

• CPU instruction extension.

• Number of source row vectors.

Platform:

AWS c5d.xlarge (Intel(R) Xeon(R) Platinum 8124M CPU @ 3.00GHz)

All test run on a single Core.

I/O = (src_num + 1) * vector_size / cost

Src Num	Vector size	AVX512 I/O (MB/S)	AVX2 I/O (MB/S)	SSE2 I/O (MB/S)
5	4KB	270403.73	142825.25	74443.91
5	1MB	26948.34	26887.37	26950.65
5	8MB	17881.32	17212.56	16402.97
10	4KB	190445.30	102953.59	53244.04
10	1MB	26424.44	26618.65	26094.39
10	8MB	15471.31	14866.72	13565.80

Documentation

Index

• Variables
• func Bytes(dst, a, b []byte) int
• func Bytes8(dst, a, b []byte)
• func Bytes16(dst, a, b []byte)
• func BytesU(dst, a, b []byte) int
• func Encode(dst []byte, src [][]byte) (n int)

Variables

var EnableAVX512 = true

EnableAVX512 may slow down CPU Clock (maybe not). TODO need more research: https://lemire.me/blog/2018/04/19/by-how-much-does-avx-512-slow-down-your-cpu-a-first-experiment/

Functions

func Bytes

func Bytes(dst, a, b []byte) int

Bytes XORs the bytes in a and b into a destination slice. The source and destination may overlap.

Bytes returns the number of bytes encoded, which will be the minimum of len(dst), len(a), len(b).

func Bytes8

func Bytes8(dst, a, b []byte)

Bytes8 XORs of word (8 Bytes). The slice arguments a, b, dst's lengths are assumed to be at least 8, if not, Bytes8 will panic.

func Bytes16

func Bytes16(dst, a, b []byte)

Bytes16 XORs of packed doubleword (16 Bytes). The slice arguments a, b, dst's lengths are assumed to be at least 16, if not, Bytes16 will panic.

func BytesU

func BytesU(dst, a, b []byte) int

BytesU XORs the bytes in a and b into a destination slice. The source and destination may overlap.

BytesU returns the number of bytes encoded, which will be the minimum of len(dst), len(a), len(b).

It's used for encoding small bytes slices (< dozens bytes), and the slices may not be aligned to 8 bytes or 16 bytes. If the length is big, use 'func Bytes(dst, a, b []byte)' instead.

func Encode

func Encode(dst []byte, src [][]byte) (n int)

Encode encodes elements from source slice into a destination slice. The source and destination may overlap. Encode returns the number of bytes encoded, which will be the minimum of len(src[i]) and len(dst).