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tun: unwind summing loop in checksumNoFold()
$ benchstat old.txt new.txt
goos: linux
goarch: amd64
pkg: golang.zx2c4.com/wireguard/tun
cpu: 12th Gen Intel(R) Core(TM) i5-12400
│ old.txt │ new.txt │
│ sec/op │ sec/op vs base │
Checksum/64-12 10.670n ± 2% 4.769n ± 0% -55.30% (p=0.000 n=10)
Checksum/128-12 19.665n ± 2% 8.032n ± 0% -59.16% (p=0.000 n=10)
Checksum/256-12 37.68n ± 1% 16.06n ± 0% -57.37% (p=0.000 n=10)
Checksum/512-12 76.61n ± 3% 32.13n ± 0% -58.06% (p=0.000 n=10)
Checksum/1024-12 160.55n ± 4% 64.25n ± 0% -59.98% (p=0.000 n=10)
Checksum/1500-12 231.05n ± 7% 94.12n ± 0% -59.26% (p=0.000 n=10)
Checksum/2048-12 309.5n ± 3% 128.5n ± 0% -58.48% (p=0.000 n=10)
Checksum/4096-12 603.8n ± 4% 257.2n ± 0% -57.41% (p=0.000 n=10)
Checksum/8192-12 1185.0n ± 3% 515.5n ± 0% -56.50% (p=0.000 n=10)
Checksum/9000-12 1328.5n ± 5% 564.8n ± 0% -57.49% (p=0.000 n=10)
Checksum/9001-12 1340.5n ± 3% 564.8n ± 0% -57.87% (p=0.000 n=10)
geomean 185.3n 77.99n -57.92%
Reviewed-by: Adrian Dewhurst <adrian@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jordan Whited
Jason A. Donenfeld
parent
4201e08f1d
commit
895d6c23cd
100
tun/checksum.go
100
tun/checksum.go
@ -3,23 +3,99 @@ package tun
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import "encoding/binary"
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// TODO: Explore SIMD and/or other assembly optimizations.
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// TODO: Test native endian loads. See RFC 1071 section 2 part B.
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func checksumNoFold(b []byte, initial uint64) uint64 {
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ac := initial
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i := 0
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n := len(b)
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for n >= 4 {
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ac += uint64(binary.BigEndian.Uint32(b[i : i+4]))
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n -= 4
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i += 4
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for len(b) >= 128 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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ac += uint64(binary.BigEndian.Uint32(b[32:36]))
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ac += uint64(binary.BigEndian.Uint32(b[36:40]))
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ac += uint64(binary.BigEndian.Uint32(b[40:44]))
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ac += uint64(binary.BigEndian.Uint32(b[44:48]))
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ac += uint64(binary.BigEndian.Uint32(b[48:52]))
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ac += uint64(binary.BigEndian.Uint32(b[52:56]))
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ac += uint64(binary.BigEndian.Uint32(b[56:60]))
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ac += uint64(binary.BigEndian.Uint32(b[60:64]))
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ac += uint64(binary.BigEndian.Uint32(b[64:68]))
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ac += uint64(binary.BigEndian.Uint32(b[68:72]))
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ac += uint64(binary.BigEndian.Uint32(b[72:76]))
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ac += uint64(binary.BigEndian.Uint32(b[76:80]))
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ac += uint64(binary.BigEndian.Uint32(b[80:84]))
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ac += uint64(binary.BigEndian.Uint32(b[84:88]))
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ac += uint64(binary.BigEndian.Uint32(b[88:92]))
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ac += uint64(binary.BigEndian.Uint32(b[92:96]))
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ac += uint64(binary.BigEndian.Uint32(b[96:100]))
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ac += uint64(binary.BigEndian.Uint32(b[100:104]))
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ac += uint64(binary.BigEndian.Uint32(b[104:108]))
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ac += uint64(binary.BigEndian.Uint32(b[108:112]))
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ac += uint64(binary.BigEndian.Uint32(b[112:116]))
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ac += uint64(binary.BigEndian.Uint32(b[116:120]))
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ac += uint64(binary.BigEndian.Uint32(b[120:124]))
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ac += uint64(binary.BigEndian.Uint32(b[124:128]))
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b = b[128:]
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}
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for n >= 2 {
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ac += uint64(binary.BigEndian.Uint16(b[i : i+2]))
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n -= 2
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i += 2
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if len(b) >= 64 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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ac += uint64(binary.BigEndian.Uint32(b[32:36]))
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ac += uint64(binary.BigEndian.Uint32(b[36:40]))
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ac += uint64(binary.BigEndian.Uint32(b[40:44]))
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ac += uint64(binary.BigEndian.Uint32(b[44:48]))
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ac += uint64(binary.BigEndian.Uint32(b[48:52]))
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ac += uint64(binary.BigEndian.Uint32(b[52:56]))
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ac += uint64(binary.BigEndian.Uint32(b[56:60]))
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ac += uint64(binary.BigEndian.Uint32(b[60:64]))
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b = b[64:]
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}
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if n == 1 {
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ac += uint64(b[i]) << 8
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if len(b) >= 32 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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b = b[32:]
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}
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if len(b) >= 16 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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b = b[16:]
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}
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if len(b) >= 8 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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b = b[8:]
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}
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if len(b) >= 4 {
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ac += uint64(binary.BigEndian.Uint32(b))
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b = b[4:]
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}
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if len(b) >= 2 {
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ac += uint64(binary.BigEndian.Uint16(b))
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b = b[2:]
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}
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if len(b) == 1 {
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ac += uint64(b[0]) << 8
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}
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return ac
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}
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35
tun/checksum_test.go
Normal file
35
tun/checksum_test.go
Normal file
@ -0,0 +1,35 @@
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package tun
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import (
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"fmt"
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"math/rand"
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"testing"
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)
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func BenchmarkChecksum(b *testing.B) {
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lengths := []int{
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64,
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128,
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256,
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512,
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1024,
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1500,
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2048,
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4096,
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8192,
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9000,
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9001,
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}
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for _, length := range lengths {
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b.Run(fmt.Sprintf("%d", length), func(b *testing.B) {
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buf := make([]byte, length)
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rng := rand.New(rand.NewSource(1))
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rng.Read(buf)
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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checksum(buf, 0)
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}
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})
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}
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}
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