Linux 5.3 Kernel to be Released

Huge amount of updates, improvements, changes and new features awaits all Linux users
17 September 2019   406

After two months of development, Linus Torvalds introduced the Linux 5.3 kernel release. Among the most notable changes: support for AMD Navi GPUs, Zhaoxi processors, and Intel Speed ​​Select power management technology, the ability to use umwait instructions to wait without using loops, increasing the interactivity utilization clamping mode for asymmetric CPUs, the pidfd_open system call, the ability to use IPv4 addresses from the subnet 0.0.0.0/8, the possibility of hardware acceleration of nftables, support for HDR in the DRM subsystem, integration of the ACRN hypervisor.

In the announcement of the new release, Linus reminded all developers of the main rule of kernel development - maintaining the invariance of behavior for user space components. Changes in the kernel should in no way violate already running applications and lead to user-level regressions. At the same time, a violation of behavior can cause not only a change in the ABI, removal of outdated code or errors, but also an indirect effect of correctly working useful improvements. As a good example, the useful optimization in Ext4 code was discarded, which reduces the number of accesses to the drive by disabling the read-ahead inode table for small I / O requests.

Optimization has led to the fact that, due to a decrease in disk activity, the entropy for the random number generator getrandom () began to accumulate more slowly and in some configurations, under certain circumstances, there could be hangs during loading until the entropy pool is full. Since the optimization is really useful, a discussion arose among the developers, in which it was proposed to eliminate the problem by disabling the default blocking mode of the getrandom () call with the addition of an optional flag to wait for entropy, but such a change will affect the quality of random numbers at the initial stage of loading. In the change rollback commit, Linus noted that he plans to bring the optimization back as soon as the problem with getrandom () is resolved.

The new version adopted 15794 patches from 1974 developers, the patch size is 92 MB (the changes affected 13986 files, 258419 lines of code were added, 599137 lines were deleted). About 39% of all the changes presented in 5.3 are related to device drivers, about 12% of changes are related to updating the code specific to hardware architectures, 11% are connected to the network stack, 3% to file systems and 3% to internal kernel subsystems.

Get more information about the new features and from the mailing.

LizardFS 3.13.0-rc2 to be Rolled Out

The release of LizardFS 3.13.0 with  Raft consensus algorithm as a main innovation is scheduled to be released in late December
12 November 2019   139

After a year-long pause in development, work on the new branch of the fault-tolerant distributed file system LizardFS 3.13 was resumed and the second candidate for releases was published. Recently there was a change of ownership of the company developing LizardFS, a new leadership was adopted and the developers changed. Over the past two years, the project has moved away from the community and did not pay due attention to it, but the new team intends to revive its previous relations with the community and establish close interaction with it. The project code is written in C and C ++ and is distributed under the GPLv3 license.

LizardFS is a distributed cluster file system that allows you to disperse data across different servers, but provide access to them in the form of a single large partition, the work with which is carried out by analogy with traditional disk partitions. The mounted section with LizardFS supports POSIX file attributes, ACLs, locks, sockets, channels, device files, symbolic and hard links. The system does not have a single point of failure, all components are redundant. Parallelization of data operations is supported (several clients can access files at the same time).

The release of LizardFS 3.13.0 is scheduled to be released in late December. The main innovation of LizardFS 3.13 is the use of the Raft consensus algorithm (using its own implementation of uRaft, which was previously used in commercial products) to ensure fault tolerance (switching master servers in the event of a failure). Using uRaft simplifies setup and reduces latency when recovering from a failure, but requires at least three working nodes, one of which is used for quorum.

Among other changes: a new client based on the FUSE3 subsystem, solving problems with error correction, the nfs-ganesha plugin was rewritten in C language. The 3.13.0-rc2 update fixes several critical errors that made the previous test releases of the 3.13 branch unsuitable for use (patches for the 3.12 branch have not yet been published, and the upgrade from 3.12 to 3.13 still leads to complete data loss).

In 2020, work will focus on developing Agama, the new completely rewritten core of LizardFS, which, according to the developers, will provide a three-fold increase in productivity compared to branch 3.12. Agama will make the transition to event-driven architecture (event driven), asio-based I / O based on asio, work primarily in user space (to reduce the dependence on kernel caching mechanisms). In addition, a new debugging subsystem and network activity analyzer with support for performance tuning will be offered.

Full support for versioning write operations will be added to the LizardFS client, which will increase the reliability of disaster recovery, solve the problems that arise when different clients share the same data, and will achieve a significant increase in performance. The client will be transferred to its own network subsystem operating in user space. The first working prototype of LizardFS based on Agama is planned to be prepared in the second quarter of 2020. At the same time, they promise to implement tools for integrating LizardFS with the Kubernetes platform.

Get more info at the official website.