Linux 4.11

This release adds support for pluggable I/O schedulers framework in the multiqueue block layer. The Linux block layer has different I/O schedulers (deadline, cfq, noop, etc) with different performance characteristics each one, and users are allowed to switch between them on the fly. In Linux 3.13 a new multiqueue design that performs better with modern hardware (eg. SSD, NVM) has been added. However, this new multiqueue design did not include support for pluggable I/O schedulers. This release solves that problem with the merge of a multiqueue-ready I/O scheduling framework. A port of the deadline scheduler has also been added.
Based in work started in Linux 4.4 this release adds journalling support to RAID4/5/6 in the MD layer. With a journal device configured (typically NVRAM or SSD) a crash during degraded operations cannot result in data corruption.
Modern storage devices such as SSDs are making the usage of swapping attractive not just as a way to deal with excessive memory load, but also as a performance enhancement technique. Cloud providers, for example, can overcommit memory more aggressively and fit more VMs to a platform with a fast swap device. However, the swapping implementation was designed for traditional rotating hard disks, where the performance and latency of the swap did not matter as much as it does with modern storage. This release makes the swap implementation more scalable, making it more suitable for use with modern storage devices.
Due to several shortcomings in the stat() system call (like not being y2038 ready or not playing well with networking filesystems), a new system call has been worked through the years, with the final result being statx() available in this kernel release.
A new perf ftrace tool has been added. This tool intends to be a front-end for the already existing ftrace interface. In this release it supports two tracers: function_graph and function.
The Opal Storage Specification is a set of specifications for features of data storage devices that enhance their security. For example, it defines a way of encrypting the stored data so that an unauthorized person who gains possession of the device cannot see the data. That is, it is a specification for self-encrypting drives (SED). This release adds Linux support for Opal nvme enabled controllers. It enables users to setup/unlock/lock locking ranges for SED devices using the Opal protocol.
This release adds optional support for scrollback history not being flushed when switching between consoles (this breaks tools like clear_console).
AMDGPU power management continues to mature with Linux 4.11. Likely due to TTM memory management improvements, Linux 4.11 is faster for RADV Vulkan.
Intel has enabled frame-buffer compression by default for Skylake hardware and newer. Also Intel’s DRM driver also now handles DisplayPort MST audio. They added multi-stream transport capabilities a few kernels ago while this work is about allowing audio for DP MST displays.
Intel also has initial Geminilake graphics support. Geminilake SoCs will be shipping later this year.
The Nouveau DRM driver went through a Secure Boot code refactoring and based off that work NVIDIA even released the signed Pascal firmware for Pascal consumer cards along with code for bringing up accelerated support for the GeForce GTX 1050/1060/1070/1080. But that accelerated Pascal support isn’t landing until Linux 4.12.
As always read the full changelog.

This entry was posted on Sunday, May 7th, 2017 at 12:56 PM and is filed under linux.

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