From ef5c587f782d944005971c7ba5da88405f9b000b Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josh@tailscale.com>
Date: Tue, 22 Mar 2022 11:23:56 -0700
Subject: [PATCH] conn: remove the final alloc per packet receive
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This does bind_std only; other platforms remain.
The remaining alloc per iteration in the Throughput benchmark
comes from the tuntest package, and should not appear in regular use.
name old time/op new time/op delta
Latency-10 25.2µs ± 1% 25.0µs ± 0% -0.58% (p=0.006 n=10+10)
Throughput-10 2.44µs ± 3% 2.41µs ± 2% ~ (p=0.140 n=10+8)
name old alloc/op new alloc/op delta
Latency-10 854B ± 5% 741B ± 3% -13.22% (p=0.000 n=10+10)
Throughput-10 265B ±34% 267B ±39% ~ (p=0.670 n=10+10)
name old allocs/op new allocs/op delta
Latency-10 16.0 ± 0% 14.0 ± 0% -12.50% (p=0.000 n=10+10)
Throughput-10 2.00 ± 0% 1.00 ± 0% -50.00% (p=0.000 n=10+10)
name old packet-loss new packet-loss delta
Throughput-10 0.01 ±82% 0.01 ±282% ~ (p=0.321 n=9+8)
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
conn/bind_std.go | 53 +++++++++++++++++++++++++++++++++---------------
1 file changed, 37 insertions(+), 16 deletions(-)
diff --git a/conn/bind_std.go b/conn/bind_std.go
index e0f6cdd..b6a7ab3 100644
--- a/conn/bind_std.go
+++ b/conn/bind_std.go
@@ -31,34 +31,34 @@ type StdNetEndpoint netip.AddrPort
var (
_ Bind = (*StdNetBind)(nil)
- _ Endpoint = (*StdNetEndpoint)(nil)
+ _ Endpoint = StdNetEndpoint{}
)
func (*StdNetBind) ParseEndpoint(s string) (Endpoint, error) {
e, err := netip.ParseAddrPort(s)
- return (*StdNetEndpoint)(&e), err
+ return asEndpoint(e), err
}
-func (*StdNetEndpoint) ClearSrc() {}
+func (StdNetEndpoint) ClearSrc() {}
-func (e *StdNetEndpoint) DstIP() netip.Addr {
- return (*netip.AddrPort)(e).Addr()
+func (e StdNetEndpoint) DstIP() netip.Addr {
+ return (netip.AddrPort)(e).Addr()
}
-func (e *StdNetEndpoint) SrcIP() netip.Addr {
+func (e StdNetEndpoint) SrcIP() netip.Addr {
return netip.Addr{} // not supported
}
-func (e *StdNetEndpoint) DstToBytes() []byte {
- b, _ := (*netip.AddrPort)(e).MarshalBinary()
+func (e StdNetEndpoint) DstToBytes() []byte {
+ b, _ := (netip.AddrPort)(e).MarshalBinary()
return b
}
-func (e *StdNetEndpoint) DstToString() string {
- return (*netip.AddrPort)(e).String()
+func (e StdNetEndpoint) DstToString() string {
+ return (netip.AddrPort)(e).String()
}
-func (e *StdNetEndpoint) SrcToString() string {
+func (e StdNetEndpoint) SrcToString() string {
return ""
}
@@ -152,24 +152,24 @@ func (bind *StdNetBind) Close() error {
func (*StdNetBind) makeReceiveIPv4(conn *net.UDPConn) ReceiveFunc {
return func(buff []byte) (int, Endpoint, error) {
n, endpoint, err := conn.ReadFromUDPAddrPort(buff)
- return n, (*StdNetEndpoint)(&endpoint), err
+ return n, asEndpoint(endpoint), err
}
}
func (*StdNetBind) makeReceiveIPv6(conn *net.UDPConn) ReceiveFunc {
return func(buff []byte) (int, Endpoint, error) {
n, endpoint, err := conn.ReadFromUDPAddrPort(buff)
- return n, (*StdNetEndpoint)(&endpoint), err
+ return n, asEndpoint(endpoint), err
}
}
func (bind *StdNetBind) Send(buff []byte, endpoint Endpoint) error {
var err error
- nend, ok := endpoint.(*StdNetEndpoint)
+ nend, ok := endpoint.(StdNetEndpoint)
if !ok {
return ErrWrongEndpointType
}
- addrPort := (*netip.AddrPort)(nend)
+ addrPort := netip.AddrPort(nend)
bind.mu.Lock()
blackhole := bind.blackhole4
@@ -186,6 +186,27 @@ func (bind *StdNetBind) Send(buff []byte, endpoint Endpoint) error {
if conn == nil {
return syscall.EAFNOSUPPORT
}
- _, err = conn.WriteToUDPAddrPort(buff, *addrPort)
+ _, err = conn.WriteToUDPAddrPort(buff, addrPort)
return err
}
+
+// endpointPool contains a re-usable set of mapping from netip.AddrPort to Endpoint.
+// This exists to reduce allocations: Putting a netip.AddrPort in an Endpoint allocates,
+// but Endpoints are immutable, so we can re-use them.
+var endpointPool = sync.Pool{
+ New: func() any {
+ return make(map[netip.AddrPort]Endpoint)
+ },
+}
+
+// asEndpoint returns an Endpoint containing ap.
+func asEndpoint(ap netip.AddrPort) Endpoint {
+ m := endpointPool.Get().(map[netip.AddrPort]Endpoint)
+ defer endpointPool.Put(m)
+ e, ok := m[ap]
+ if !ok {
+ e = Endpoint(StdNetEndpoint(ap))
+ m[ap] = e
+ }
+ return e
+}