XDP: From zero to 14 Mpps
In past years, the kernel community has been using different approaches in the quest for ever-increasing networking performance. While improvements have been measurable in several areas, a new wave of architecture-related security issues and related counter-measures has undone most of the gains, and purely in-kernel solutions for some packet-processing intensive workloads still lag behind the bypass solution, namely Data Plane Development Kit (DPDK), by almost an order of magnitude.
But the kernel community never sleeps (almost literally) and the holy grail of kernel-based networking performance has been found under the name of XDP: the eXpress Data Path. XDP is available in Red Hat Enterprise Linux 8 Beta, which you can download and run now.
Continue reading “Achieving high-performance, low-latency networking with XDP: Part I”
Networks are fun to work with, but often they are also a source of trouble. Network troubleshooting can be difficult, and reproducing the bad behavior that is happening in the field can be painful as well.
Luckily, there are some tools that come to the aid: network namespaces, virtual machines,
netfilter. Simple network setups can be reproduced with network namespaces and
veth devices, while more-complex setups require interconnecting virtual machines with a software bridge and using standard networking tools, like
tc, to simulate the bad behavior. If you have an issue with ICMP replies generated because an SSH server is down,
iptables -A INPUT -p tcp --dport 22 -j REJECT --reject-with icmp-host-unreachable in the correct namespace or VM can do the trick.
This article describes using eBPF (extended BPF), an extended version of the Berkeley Packet Filter, to troubleshoot complex network issues. eBPF is a fairly new technology and the project is still in an early stage, with documentation and the SDK not yet ready. But that should improve, especially with XDP (eXpress Data Path) being shipped in Red Hat Enterprise Linux 8 Beta, which you can download and run now.
Continue reading “Network debugging with eBPF (RHEL 8 Beta)”