July 2, 2018

Linux Weather Forecast

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Linux forecast
Linux "chief meteorologist" Jonathan Corbet shares the current conditions for Linux kernel development.

Welcome to the Linux Weather Forecast

This page is an attempt to track ongoing developments in the Linux development community that have a good chance of appearing in a mainline kernel and/or major distributions sometime in the near future. Your "chief meteorologist" is Jonathan Corbet, Executive Editor at LWN.net. If you have suggestions on improving the forecast (and particularly if you have a project or patchset that you think should be tracked), please add your comments below. 

Forecast Summaries

Current conditions: the 4.17 kernel was released on June 3; some of the more important additions in this kernel are::

  • Some significant scheduler improvements that, in particular, will help with energy-efficient scheduling on mobile devices.
  • Support for the unloved blackfin, cris, frv, m32r, metag, mn10300, score, and tile architectures has been removed. This change will result in 4.17 being smaller (in terms of lines of code) than 4.16 — only the third time that has happened in the history of the kernel project.
  • Support for the receiving TLS-encrypted data has been added to the kernel.
  • The tracing subsystem has gained support for histogram triggers, making it easier to aggregate event data in the kernel without needing to write BPF programs.

In addition to that, of course, is a long list of bug fixes, code cleanups, and more. The 4.17 kernel was the work of 1,700 developers who contributed over 13,500 individual changes; see this article for more information on where 4.17 came from.

Short-term forecast: the 4.18 kernel can be expected in early August. There are a number of changes coming in this release, including:

  • The power domains subsystem has seen a number of enhancements that will lead to improved whole-system power management.
  • It is now possible for unprivileged processes to mount filesystems when running in a user namespace. This will make it possible to mount filesystems within containers without the need for additional privileges.
  • Zero-copy TCP data reception is now supported.
  • The AF_XDP subsystem will eventually lead to highly accelerated networking in a number of settings. This work is part of a larger effort to win back users of user-space networking stacks by providing better facilities in the kernel.
  • Bpfilter is a new packet-filtering mechanism based on the BPF virtual machine. The 4.18 version of bpfilter won't do much, but it is expected to be the base on which the next generation of kernel firewalling systems is built.
  • Restartable sequences, a new API for performing highly optimized lockless operations in user space, have finally made it into the mainline kernel.

It's also worth noting that the new AIO-based polling mechanism, originally merged for 4.18, has been reverted pending further work. 4.18 is in the stabilization phase now, so there should be no new features merged during this development cycle.

This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License.

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