What's New in Linux 3.14

Linux 3.14

Linux 3.14 was released on March 31st 2014, after the normal two months or so of development, the previous version having been released on January 20th. This version number is both an approximation of pi to two digits and a match for the month/year 3/14.

So much for trivia, what's new?

Source

Deadline scheduler

The deadline scheduler was finally merged for 3.14 after having been in development for several years. It offers real time systems another way to schedule tasks: instead of setting priorities, processes provide three parameters: runtime, period, and deadline.

Tasks are guaranteed an execution slice of length runtime every period length within deadline of the period start. So, for example, with runtime=1µs, period=100µs, deadline=10µs, the task would be guaranteed to get at least 1µs of execution time within the first 10µs of the period. Processes with a shorter/closer deadline will get executed first by the scheduler.

This should allow Linux to work better in hard realtime applications.

KASLR

KASLR is one of the more indecipherable acronyms out there. It stands for Kernel Address Space Layout Randomization. It's an implementation of ASLR for kernel memory, meaning that the physical and virtual addresses of kernel memory start at a random location.

The idea is to make certain exploits more difficult to run and more likely to cause random breakage that the administrator can detect. 64-bit installs benefit more from randomization due to the larger available address space.

zram

The zram memory compression system has been in staging for quite a while and is now considered stable. Google is using this in their Chrome OS, so anyone with a Chromebook or a Chromebox will probably already have it running:

Since Chrome OS was mentioned: the main reason why we don't use swap to a disk (rotating or SSD) is because it doesn't degrade gracefully and leads to a bad interactive experience. Generally we prefer to manage RAM at a higher level, by transparently killing and restarting processes. But we noticed that zram is fast enough to be competitive with the latter, and it lets us make more efficient use of the available RAM.

Contributors to 3.14

Company/Group
Changesets
Lines Changed
Intel
8.9%
10.0%
Red Hat
7.3%
6.7%
Linaro
4.4%
1.9%
Largest contributors by changesets according to Jonathan Corbet: http://lwn.net/Articles/590354/

Maintenance length

How long a particular kernel version gets stable updates depends on what it gets used for and who wants to support it. All releases get updates until the next release, which will be in some two months or a bit more. Greg KH maintains two longterm releases in addition, but the next one is only scheduled to be selected around October. Red Hat doesn't plan to use 3.14, so that avenue is also out.

Ubuntu is still a bit of an unknown. The next Ubuntu release will be out in a April, so they will probably stick with 3.13, but if they do upgrade to 3.14 before release, they will support 3.14 for five years.

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