Brad Fitzpatrick 47debc5a6f derp/derpserver: don't build debug log arguments on the packet path
sclient.debugLogf and Server.debugLogf check a debug flag before
logging, but Go evaluates and boxes their arguments before the call.
The per-packet call sites in run, handleFrameSendPacket,
handleFrameForwardPacket, sendPkt, recordDrop, and sendPacket's
deferred stats func were therefore calling key.NodePublic.ShortString
and boxing frame headers on every relayed packet, all for messages
that were then discarded.

On one busy server's heap profile, those discarded arguments were
about half of all objects allocated by the process. Guard each hot
call site with the debug flag so nothing is built unless it will be
logged, and document that requirement on both debugLogf methods.

While here, give the sender cardinality sketch its key bytes from a
stack array rather than an AppendTo(nil) allocation per packet.

BenchmarkSendRecv drops from 10 or 11 allocations per relayed packet
to 3, and BenchmarkConcurrentStreams from 11 to 4.

Updates #21064

Change-Id: Ibb7c4fbff546b6f1b40ce0a21d41ae0976705941
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-09-18 06:52:51 -07:00
2026-09-16 10:08:11 -04:00
2026-09-03 15:37:10 -07:00
2026-07-10 17:39:16 -07:00
2026-09-17 21:36:46 -07:00
2026-09-17 17:22:32 -04:00
2026-01-27 16:15:17 -08:00
2026-06-02 10:59:29 -07:00
2026-08-28 12:47:04 -07:00
2026-09-17 16:55:23 -07:00

Tailscale

https://tailscale.com

Private WireGuard® networks made easy

Overview

This repository contains the majority of Tailscale's open source code. Notably, it includes the tailscaled daemon and the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows, macOS, and to varying degrees on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's code, but this repo doesn't contain the mobile GUI code.

Other Tailscale repos of note:

For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.

Using

We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.

Other clients

The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.

Building

We always require the latest Go release, currently Go 1.27. (While we build releases with our Go fork, its use is not required.)

go install tailscale.com/cmd/tailscale{,d}

If you're packaging Tailscale for distribution, use build_dist.sh instead, to burn commit IDs and version info into the binaries:

./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled

If your distro has conventions that preclude the use of build_dist.sh, please do the equivalent of what it does in your distro's way, so that bug reports contain useful version information.

Bugs

Please file any issues about this code or the hosted service on the issue tracker.

Contributing

PRs welcome! But please file bugs. Commit messages should reference bugs.

We require Developer Certificate of Origin Signed-off-by lines in commits.

See commit-messages.md (or skim git log) for our commit message style.

About Us

Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:

WireGuard is a registered trademark of Jason A. Donenfeld.

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