README
¶
tc_cpumap
In normal operation, TC is limited to a single classful qdisc per interface and because TC qdiscs require a global lock to operate this effectively limits TC to a single CPU core. This is known as the qdisc locking problem.
One solution to this problem is to build independent classful qdiscs per CPU core and map packets to these CPU cores (e.g. by IP prefix). The eBPF XDP cpumap feature is used to redirect packets to the right CPU core based on IP prefix, eBPF is also used to set the appropriate NIC TX queue and TC class ID for each packet.
This project is largely based on the work of the following projects:
Features
- Supports handling SNAT traffic
- Supports multiple LAN interfaces
- Capture basic traffic statistics (byte and packet counters)
Requirements
- Minimum of 2 network interfaces (1x WAN and 1x LAN)
- Network interfaces must have multiple TX and RX queues
- Linux 5.17+ (Linux 6+ is recommended)
Downloading
Download prebuilt binaries from GitHub.
Building
Binaries can be compiled from source by using the following instructions:
Install build dependencies
First, install the build dependencies:
Ubuntu
apt install clang curl linux-tools-common linux-tools-$(uname -r) llvm
Debian
apt install bpftool clang curl llvm
Build
Second, build binaries with GoReleaser:
./build.sh
Running
To load the eBPF programs into the kernel and attach to the network interfaces, run:
sudo tc_cpumap --wan eno1 --lan eno2
It is also possible to configure tc_cpumap by using envionment variables:
sudo TC_CPUMAP_WAN="eno1" TC_CPUMAP_LAN="eno2 eno3" tc_cpumap
Configuring
First, load the TC qdiscs and classes, xdp-cpumap-tc provides an example script that shows how to do this.
Second, prepare a configuration file that maps IP prefixes to CPUs and TC classes, an example config is provided to show the format.
Third, load the configuration file to activate the system.
sudo tc_cpumap_config update --config tc-cpumap.yml
Traffic statistics
Current traffic statistics can be printed by running the following command:
sudo tc_cpumap_trafficstats
Directories