Files
nebula/udp/connsock_bench_darwin_test.go
T
Ryan HuberandClaude Opus 5.5 21075ba32e udp/darwin: batch receives and connected-socket sends with recvmsg_x/sendmsg_x
internal/msgx is the one copy of xnu's private batched socket calls: the
msghdr_x layout, Send/Recv through the raw syscall (EINTR retried) and
Unsupported for the errnos a kernel or sandbox refuses them with.

Every socket the listener owns reads with recvmsg_x: the listener and each
connected socket run their own reader goroutine, and hand whole batches to
ListenOut over a channel. ListenOut runs the EncReader over a batch and
flushes once, so the reader stays single-threaded without a lock that
readers contend on, and the next recvmsg_x overlaps the decrypt of the last
batch. Batch buffers (64 x MTU) come from a per-listener free list that
keeps up to 11; a reader takes one only while its socket is readable, so
idle connected sockets hold none. A batch with a header intact msghdr_x
entries can't produce, or ENOSYS/EPERM/EOPNOTSUPP, switches every reader to
one datagram per read for good.

Connected sockets send runs with sendmsg_x, which xnu batches through the
stack on a connected socket. EAGAIN/ENOBUFS keep #1901's single-datagram
stall handling; a refused sendmsg_x retries the datagram with write and
turns sendmsg_x off once that goes through.

The connected-socket knobs lose their NEBULA_CONNSOCK* environment
overrides and keep #1901's defaults.

Based on Caleb Jasik's #1895 (recvmsg_x) and #1897 (sendmsg_x), and Jack
Doan's internal/msgx shape from #1898.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-30 11:11:48 +00:00

107 lines
3.2 KiB
Go

//go:build !e2e_testing
package udp
import (
"log/slog"
"net"
"net/netip"
"testing"
"time"
)
// benchConnSocks opens a wildcard listener with ListenOut running and cfg applied, and a loopback peer that never
// reads, so its sends cost only the sender.
func benchConnSocks(b *testing.B, s Settings, cfg func(*connSockConfig)) (*StdConn, netip.AddrPort) {
b.Helper()
c, err := NewListener(slog.New(slog.DiscardHandler), s)
if err != nil {
b.Fatal(err)
}
b.Cleanup(func() { _ = c.Close() })
u := c.(*StdConn)
if cfg != nil {
cfg(&u.socks.cfg)
}
go func() { _ = u.ListenOut(func(netip.AddrPort, []byte) {}, func() {}) }()
for !u.listening.Load() {
time.Sleep(time.Millisecond)
}
pc, err := net.ListenPacket("udp4", "127.0.0.1:0")
if err != nil {
b.Fatal(err)
}
b.Cleanup(func() { _ = pc.Close() })
return u, pc.LocalAddr().(*net.UDPAddr).AddrPort()
}
// BenchmarkConnSockWriteTo measures one WriteTo of a full-size datagram down each path: the listener with
// connected sockets off, to a destination that is no tunnel's remote while another is, to an established peer
// that never gets busy, and on a connected socket.
func BenchmarkConnSockWriteTo(b *testing.B) {
pkt := make([]byte, 1400)
cases := []struct {
name string
cfg func(*connSockConfig)
setup func(b *testing.B, u *StdConn, dst netip.AddrPort)
}{
{name: "listener/off", cfg: func(c *connSockConfig) { c.max = 0 }},
{name: "listener/ineligible", setup: func(b *testing.B, u *StdConn, dst netip.AddrPort) {
u.SetEstablishedPeer(netip.AddrPortFrom(dst.Addr(), dst.Port()+1), true)
}},
{name: "listener/eligible-not-busy", cfg: func(c *connSockConfig) { c.run = 1 << 30 },
setup: func(b *testing.B, u *StdConn, dst netip.AddrPort) { u.SetEstablishedPeer(dst, true) }},
{name: "connected", setup: func(b *testing.B, u *StdConn, dst netip.AddrPort) {
u.SetEstablishedPeer(dst, true)
for range u.socks.cfg.run {
_ = u.WriteTo(pkt, dst)
}
if u.connSockFor(dst) == nil {
b.Fatal("no connected socket")
}
}},
}
for _, c := range cases {
b.Run(c.name, func(b *testing.B) {
u, dst := benchConnSocks(b, Settings{Listen: netip.MustParseAddrPort("0.0.0.0:0")}, c.cfg)
if c.setup != nil {
c.setup(b, u, dst)
}
b.ReportAllocs()
b.ResetTimer()
for range b.N {
_ = u.WriteTo(pkt, dst)
}
})
}
}
// BenchmarkConnSockDispatch measures what WriteTo adds before the listener's sendto, without the syscall: a v4
// listener refuses a v6 destination before sending, with connected sockets off or with another peer established.
func BenchmarkConnSockDispatch(b *testing.B) {
pkt := make([]byte, 1400)
dst := netip.MustParseAddrPort("[::1]:4242")
for _, c := range []struct {
name string
cfg func(*connSockConfig)
establish bool
}{
{name: "off", cfg: func(c *connSockConfig) { c.max = 0 }},
{name: "ineligible", establish: true},
} {
b.Run(c.name, func(b *testing.B) {
u, peer := benchConnSocks(b, Settings{Listen: netip.MustParseAddrPort("127.0.0.1:0"), Multi: true}, c.cfg)
if c.establish {
u.SetEstablishedPeer(peer, true)
}
b.ReportAllocs()
b.ResetTimer()
for range b.N {
if u.WriteTo(pkt, dst) == nil {
b.Fatal("sent a v6 datagram on a v4 listener")
}
}
})
}
}