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Linux kernel 5.3 has been released!

Main innovations

  • The pidfd mechanism allows you to assign a specific PID to a process. Pinning continues after the process is terminated so that the PID can be issued to it when it starts again. Details.
  • Limitations of frequency ranges in the process scheduler. For example, critical processes can be run at a minimum frequency threshold (say, no less than 3 GHz), and low-priority processes can be run at a higher frequency threshold (for example, no more than 2 GHz). Details.
  • Support for AMD Navi family video chips (RX5700) in the amdgpu driver. All necessary functionality is implemented, including video encoding/decoding and power management.
  • Fully run on x86-compatible Zhaoxin processors, created as a result of collaboration between VIA and the Shanghai government.
  • Power management subsystem using Intel Speed ​​Select technology, characteristic of some processors of the Xeon family. The technology is notable for its ability to fine-tune performance for each CPU core.
  • An energy efficient user space process wait mechanism using umwait instructions for Intel Tremont processors. Details.
  • The range 0.0.0.0/8 is approved for use, which gives 16 million new IPv4 addresses. Details.
  • Flexible, lightweight ACRN hypervisor, well suited for managing IoT systems (Internet of Things). Details.

Below are some other changes.

Main part of the core

  • Support for compressing firmware into xz format, which allows you to reduce the /lib/firmware directory from ~420 MB to ~130 MB.
  • A new variant of the clone() system call with the ability to set more flags. Details.
  • Automatic selection of larger font for high resolutions in the console.
  • The CONFIG_PREEMPT_RT option marks the rapid integration of a set of RT patches into the main kernel branch.

File subsystem

  • BULKSTAT and INUMBERS system calls for XFS v5, and work has also begun on implementing multi-threaded inode traversal.
  • Btrfs now uses fast checksums (crc32c) on all architectures.
  • The immutability (immutability) flag is now strictly applied to open files on Ext4. Implemented support for holes in directories.
  • CEPH has learned to work with SELinux.
  • The smbdirect mechanism in CIFS is no longer considered experimental. Added cryptographic algorithms for SMB3.1.1 GCM. Increased file opening speed.
  • F2FS can host swap files; they operate in direct access mode. Ability to disable the garbage collector with checkpoint=disable.
  • NFS clients can establish multiple TCP connections to a server at once via the nconnect=X mount option.

Memory subsystem

  • Each dma-buf is given a full inode. The /proc/*/fd and /proc/*/map_files directories provide a lot of detailed information about shmem buffer usage.
  • The smaps engine displays separate information about anonymous memory, shared memory, and the file cache in the smaps_rollup proc file.
  • Using rbtree for swap_extent improved performance when many processes were actively swapping.
  • /proc/meminfo displays the number of vmalloc pages.
  • The capabilities of tools/vm/slabinfo have been expanded in terms of sorting caches by degree of fragmentation.

Virtualization and Security

  • The virtio-iommu driver for a paravirtualized device that allows sending IOMMU requests without emulating address tables.
  • The virtio-pmem driver for accessing drives through the physical address space.
  • Acceleration of access to metadata for vhost. For TX PPS tests show a 24% increase in speed.
  • Zerocopy is disabled by default for vhost_net.
  • Encryption keys can be attached to namespaces.
  • Support for xxhash, an extremely fast non-cryptographic hashing algorithm whose speed is limited only by memory performance.

Network subsystem

  • Initial support for nexthop objects designed to improve scalability of IPv4 and IPv6 routes.
  • Netfilter has learned to offload filtering to hardware acceleration devices. Added native connection tracking support for bridges.
  • A new traffic control module that allows you to manipulate MPLS packet headers.
  • The isdn4linux subsystem has been removed.
  • LE pings available for Bluetooth.

Hardware architectures

  • New ARM platforms and devices: Mediatek mt8183, Amlogic G12B, Kontron SMARC SoM, Google Cheza, devkit for Purism Librem5, Qualcomm Dragonboard 845c, Hugsun X99 TV Box, etc.
  • For x86, the /proc/ mechanism has been added /arch_status to display architecture-specific information such as the last time the AVX512 was used.
  • Optimized VMX performance for KVM, vmexit speed increased by 12%.
  • Added and updated various information about Intel KabyLake, AmberLake, WhiskeyLake and Ice Lake processors.
  • lzma and lzo compression for uImage on PowerPC.
  • Secure virtio-virtualization for S390.
  • Support for large memory pages for RISCV.
  • Time travel mode for User-mode Linux (time slowdown and acceleration).

Device drivers

  • HDR metadata recognition for amdgpu and i915 drivers.
  • Functionality extensions for Vega12 and Vega20 video chips in amdgpu.
  • Multi-segment gamma correction for i915, as well as asynchronous screen power-off and a number of new firmware.
  • The Nouveau video driver has learned to recognize chips from the TU116 family.
  • New Bluetooth protocols MediaTek MT7663U and MediaTek MT7668U.
  • TLS TX HW offload for Infiniband, as well as enhanced hardware and temperature monitoring.
  • Recognition of Elkhart Lake in the HD Audio driver.
  • New audio devices and codecs: Conexant CX2072X, Cirrus Logic CS47L35/85/90, Cirrus Logic Madera, RT1011/1308.
  • Apple SPI driver for keyboard and trackpad.
  • In the watchdog subsystem, you can set a time limit for opening /dev/watchdogN.
  • The cpufreq frequency control mechanism is supported by imx-cpufreq-dt and Raspberry Pi.

Source: linux.org.ru

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