mirror of https://github.com/tailscale/tailscale/
go.mod,net/tstun,wgengine/netstack: implement gVisor TCP GRO for Linux (#12921)
This commit implements TCP GRO for packets being written to gVisor on
Linux. Windows support will follow later. The wireguard-go dependency is
updated in order to make use of newly exported IP checksum functions.
gVisor is updated in order to make use of newly exported
stack.PacketBuffer GRO logic.
TCP throughput towards gVisor, i.e. TUN write direction, is dramatically
improved as a result of this commit. Benchmarks show substantial
improvement, sometimes as high as 2x. High bandwidth-delay product
paths remain receive window limited, bottlenecked by gVisor's default
TCP receive socket buffer size. This will be addressed in a follow-on
commit.
The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.
The first result is from commit 57856fc without TCP GRO.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 4.77 GBytes 4.10 Gbits/sec 20 sender
[ 5] 0.00-10.00 sec 4.77 GBytes 4.10 Gbits/sec receiver
The second result is from this commit with TCP GRO.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 10.6 GBytes 9.14 Gbits/sec 20 sender
[ 5] 0.00-10.00 sec 10.6 GBytes 9.14 Gbits/sec receiver
Updates #6816
Signed-off-by: Jordan Whited <jordan@tailscale.com>
pull/12967/head
Jordan Whited
3 months ago
committed by
GitHub
parent
cc370314e7
commit
f0230ce0b5
@ -0,0 +1,112 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package netstack
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import (
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"bytes"
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"net/netip"
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"testing"
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"gvisor.dev/gvisor/pkg/tcpip"
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"gvisor.dev/gvisor/pkg/tcpip/header"
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"tailscale.com/net/packet"
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)
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func Test_rxChecksumOffload(t *testing.T) {
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payloadLen := 100
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tcpFields := &header.TCPFields{
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SrcPort: 1,
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DstPort: 1,
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SeqNum: 1,
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AckNum: 1,
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DataOffset: 20,
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Flags: header.TCPFlagAck | header.TCPFlagPsh,
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WindowSize: 3000,
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}
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tcp4 := make([]byte, 20+20+payloadLen)
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ipv4H := header.IPv4(tcp4)
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ipv4H.Encode(&header.IPv4Fields{
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SrcAddr: tcpip.AddrFromSlice(netip.MustParseAddr("192.0.2.1").AsSlice()),
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DstAddr: tcpip.AddrFromSlice(netip.MustParseAddr("192.0.2.2").AsSlice()),
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Protocol: uint8(header.TCPProtocolNumber),
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TTL: 64,
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TotalLength: uint16(len(tcp4)),
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})
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ipv4H.SetChecksum(^ipv4H.CalculateChecksum())
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tcpH := header.TCP(tcp4[20:])
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tcpH.Encode(tcpFields)
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pseudoCsum := header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipv4H.SourceAddress(), ipv4H.DestinationAddress(), uint16(20+payloadLen))
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tcpH.SetChecksum(^tcpH.CalculateChecksum(pseudoCsum))
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tcp6ExtHeader := make([]byte, 40+8+20+payloadLen)
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ipv6H := header.IPv6(tcp6ExtHeader)
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ipv6H.Encode(&header.IPv6Fields{
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SrcAddr: tcpip.AddrFromSlice(netip.MustParseAddr("2001:db8::1").AsSlice()),
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DstAddr: tcpip.AddrFromSlice(netip.MustParseAddr("2001:db8::2").AsSlice()),
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TransportProtocol: 60, // really next header; destination options ext header
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HopLimit: 64,
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PayloadLength: uint16(8 + 20 + payloadLen),
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})
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tcp6ExtHeader[40] = uint8(header.TCPProtocolNumber) // next header
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tcp6ExtHeader[41] = 0 // length of ext header in 8-octet units, exclusive of first 8 octets.
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// 42-47 options and padding
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tcpH = header.TCP(tcp6ExtHeader[48:])
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tcpH.Encode(tcpFields)
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pseudoCsum = header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipv6H.SourceAddress(), ipv6H.DestinationAddress(), uint16(20+payloadLen))
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tcpH.SetChecksum(^tcpH.CalculateChecksum(pseudoCsum))
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tcp4InvalidCsum := make([]byte, len(tcp4))
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copy(tcp4InvalidCsum, tcp4)
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at := 20 + 16
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tcp4InvalidCsum[at] = ^tcp4InvalidCsum[at]
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tcp6ExtHeaderInvalidCsum := make([]byte, len(tcp6ExtHeader))
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copy(tcp6ExtHeaderInvalidCsum, tcp6ExtHeader)
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at = 40 + 8 + 16
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tcp6ExtHeaderInvalidCsum[at] = ^tcp6ExtHeaderInvalidCsum[at]
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tests := []struct {
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name string
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input []byte
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wantPB bool
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}{
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{
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"tcp4 packet valid csum",
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tcp4,
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true,
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},
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{
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"tcp6 with ext header valid csum",
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tcp6ExtHeader,
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true,
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},
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{
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"tcp4 packet invalid csum",
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tcp4InvalidCsum,
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false,
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},
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{
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"tcp6 with ext header invalid csum",
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tcp6ExtHeaderInvalidCsum,
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false,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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p := &packet.Parsed{}
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p.Decode(tt.input)
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got := rxChecksumOffload(p)
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if tt.wantPB != (got != nil) {
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t.Fatalf("wantPB = %v != (got != nil): %v", tt.wantPB, got != nil)
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}
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if tt.wantPB {
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gotBuf := got.ToBuffer()
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if !bytes.Equal(tt.input, gotBuf.Flatten()) {
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t.Fatal("output packet unequal to input")
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}
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}
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})
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}
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}
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