Practical Technology

In 1992, the Berkeley Packet Filter (BPF) was introduced in Unix circles as a new, improved network packet filter. Nice, but not that big a deal. Then, in 2014, it was changed and brought into the Linux kernel as extended BPF (eBPF). Again, that was okay. Just okay. Soon thereafter though, developers started using it to run user-space code inside a virtual machine (VM) on the Linux kernel.  And, then it was a huge deal. As Netflix computer performance expert Brendan Gregg said, with eBPF, “superpowers have finally come to Linux.”

What superpowers? eBPF gives you the power to run programs in the Linux kernel without changing the kernel source code or adding additional modules. In effect, it acts as a lightweight (VM) inside the Linux kernel space. There, programs that can run in eBPF run much faster, while taking advantage of kernel features unavailable to other higher-level Linux programs.

Solo BumbleBee makes Linux eBPF programming easier. More>

Last year, Linux’s source code came to a whopping 27.8 million lines of code. It’s only gotten bigger since then. Like any 30-year old software project, Linux has picked up its fair share of cruft over the years. Now, after months of work, senior Linux kernel developer Ingo Molnar is releasing his first stab at cleaning it up at a fundamental level with his “Fast Kernel Headers” project.

The object? No less than a comprehensive clean-up and rework of the Linux kernel’s header hierarchy and header dependencies. Linux contains many header, .h, files. To be exact there are about 10,000 main .h headers in the Linux kernel with the include/ and arch/*/include/ hierarchies. As Molnar explained, “Over the last 30+ years they have grown into a complicated & painful set of cross-dependencies we are affectionately calling ‘Dependency Hell’.”

Cleaning up the Linux kernel's 'Dependency Hell': This developer is proposing 2,200 commit changes. More>