joshenders

How to improve tailscale throughput via transport layer offloading in OpenWrt 24.10

Tailscale version 1.54 or later used with OpenWrt 24.10 or later (which uses kernel 6.6) enables UDP throughput improvements via transport layer offloading.

Namely, tuning two features may show improved throughput:

• rx-udp-gro-forwarding: Enables UDP Generic Receive Offload (GRO) forwarding, which aggregates incoming UDP packets to reduce CPU overhead on receive.
• rx-gro-list: If disabled (off), it prevents multiple flows from being aggregated simultaneously which simplifies flow handling and performance on some workloads.

[!NOTE]

joshenders

OpenWrt 24.10 Setup Under Incus 6.0.x on Debian 12 with PCI Passthrough

Install lxd via apt and configure

apt install incus

Configure lxd

The example config below uses the dir storage driver and no bridging since we'll be using PCI passthrough.

joshenders

Flatcar Container Linux Setup Under Incus on Debian

In case you missed it, Canonical relicensed LXD under AGPLv3 in December 2023 with a mandatory CLA. The LXD project was hard forked as Incus and licensed under an Apache 2.0 License.

Incus is maintained by the same team of developers that first created LXD and is recommended for new users going forward.

Install and configure

Borrowed from here.

joshenders

Stop making swap partitions—use swap files instead!

Swap files have had the same performance characteristics as swap partitions for almost 20 years[1] and yet, linux distributions continue to encourage the use of swap partitions during install.

Swap files are easier to use/add/remove/modify/extend after installation. They're better in every way––use swap files!

1. Create a swap file.

💡 You can use dd for this too but if your filesystem supports it, fallocate is faster.

joshenders

This guide is out of date.

See the updated guide for installing OpenWrt 24.10 on Incus 6.x, and Debian 12

OpenWrt 23.05.x Setup Under LXD 5.x on Debian 12 with PCI Passthrough

In case you missed it, Canonical relicensed LXD under AGPLv3 in December 2023 with a mandatory CLA. The LXD project was hard forked as Incus and licensed under an Apache 2.0 License.

Incus is maintained by the same team of developers that first created LXD and is recommended for new users going forward.

joshenders

Importing Hand-Rolled C Header Files in LLDB

Scenario

• We're debugging a dylib, libhello.dylib
• The dylib is linked from hello
• The exported function is helloworld()
• We do not have source, but have reversed a struct from the library and created a hand-crafted header file

Header File

joshenders

Getting started with Nintendo Switch Development using devkitpro on macOS

Prerequsite: Ensure Xcode command line tools are installed

xcode-select --install

Install the devkitpro Package Manager

joshenders

Making a UEFI bootable iPXE USB drive

Build the UEFI executable for iPXE

# First we'll clone iPXE
$ git clone git://git.ipxe.org/ipxe.git
# Go into the src directory of the cloned git repo
$ cd ipxe/src
# Compile the UEFI iPXE executable

joshenders

--- debian/varnish.init	2016-12-13 01:13:34.465123880 +0000
+++ debian/varnish.init.new	2016-12-13 01:18:50.215749771 +0000
@@ -88,8 +88,10 @@
     log_daemon_msg "Reloading $DESC" "$NAME"
     if /usr/share/varnish/reload-vcl -q; then
         log_end_msg 0
+        return 0
     else
         log_end_msg 1
+        return 1

joshenders

Background

The current verison of NodeJS hardcodes the path where perf data is written when the --perf-basic-prof flag is used.

https://github.com/v8/v8/blob/061c2ab23a1d4cd192b935e7912e7dfb1fed845d/src/log.cc#L236

At Pinterest, /tmp has limited capacity and so we weren't able to utilize perf data to troubleshoot NodeJS without filling the disk and crashing the running system.

How to patch

First I'll copy the system node binary to my local directory so this set of actions isn't destructive to the running system: