Update README for arm64 asm; latest benchmarks

README.md

@@ -3,8 +3,7 @@
 [![Go Reference](https://pkg.go.dev/badge/github.com/cespare/xxhash/v2.svg)](https://pkg.go.dev/github.com/cespare/xxhash/v2)
 [![Test](https://github.com/cespare/xxhash/actions/workflows/test.yml/badge.svg)](https://github.com/cespare/xxhash/actions/workflows/test.yml)
 
-xxhash is a Go implementation of the 64-bit
-[xxHash](http://cyan4973.github.io/xxHash/) algorithm, XXH64. This is a
+xxhash is a Go implementation of the 64-bit [xxHash] algorithm, XXH64. This is a
 high-quality hashing algorithm that is much faster than anything in the Go
 standard library.
 
@@ -25,9 +24,11 @@ func (*Digest) WriteString(string) (int, error)
 func (*Digest) Sum64() uint64
 ```
 
-The package is written with optimized pure Go and also contains an even faster
-assembly implementation for amd64. If desired, the `purego` build tag opts into
-using the Go code even on amd64.
+The package is written with optimized pure Go and also contains even faster
+assembly implementations for amd64 and arm64. If desired, the `purego` build tag
+opts into using the Go code even on those architectures.
+
+[xxHash]: http://cyan4973.github.io/xxHash/
 
 ## Compatibility
 
@@ -46,19 +47,20 @@ I recommend using the latest release of Go.
 Here are some quick benchmarks comparing the pure-Go and assembly
 implementations of Sum64.
 
-| input size | purego | asm |
-| --- | --- | --- |
-| 4 B   |  1052.65 MB/s |  1278.48 MB/s  |
-| 100 B | 6816.82 MB/s | 7881.09 MB/s  |
-| 4 KB  | 11924.07 MB/s | 17323.63 MB/s |
-| 10 MB | 11205.21 MB/s | 15484.85 MB/s |
+| input size | purego    | asm       |
+| ---------- | --------- | --------- |
+| 4 B        |  1.3 GB/s |  1.2 GB/s |
+| 16 B       |  2.9 GB/s |  3.5 GB/s |
+| 100 B      |  6.9 GB/s |  8.1 GB/s |
+| 4 KB       | 11.7 GB/s | 16.7 GB/s |
+| 10 MB      | 12.0 GB/s | 17.3 GB/s |
 
-These numbers were generated on Ubuntu 18.04 with an Intel i7-8700K CPU using
-the following commands under Go 1.17:
+These numbers were generated on Ubuntu 20.04 with an Intel Xeon Platinum 8252C
+CPU using the following commands under Go 1.19.2:
 
 ```
-go test -tags purego -benchtime 10s -bench 'Sum64$'
-go test -benchtime 10s -bench 'Sum64$'
+benchstat <(go test -tags purego -benchtime 500ms -count 15 -bench 'Sum64$')
+benchstat <(go test -benchtime 500ms -count 15 -bench 'Sum64$')
 ```
 
 ## Projects using this package