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LWN.net is a comprehensive source of news and opinions from and about the Linux community. This is the main LWN.net feed, listing all articles which are posted to the site front page.
Updated: 2 hours 53 min ago

[$] get_user_pages(), pinned pages, and DAX

Tuesday 7th of May 2019 08:14:32 PM
The problems associated with the kernel's internal get_user_pages() function have been a topic of discussion at the Linux Storage, Filesystem, and Memory-Management Summit for a few years. At the 2019 event, Jan Kara began a plenary session by saying that it would be "like last year's session". It turned out rather differently, though, perhaps due to the plenary setting; this discussion (along with the related session that followed) turned out to be one of the most heated at the entire conference.

Red Hat Enterprise Linux 8 released

Tuesday 7th of May 2019 06:00:11 PM
Red Hat has announced the release of Red Hat Enterprise Linux 8. "Modern IT is hybrid IT. But turning a sprawling ecosystem—from traditional datacenters to public cloud services—into a true hybrid environment requires a few things. Scaling as needed. Moving workloads seamlessly. Developing and managing applications that run anywhere. There's an operating system that makes those things possible. And now it gives you predictive analytics and remediation." See the release notes for more information.

[$] Remote memory control-group charging

Tuesday 7th of May 2019 05:35:58 PM
Memory control groups exist to track and limit the amount of memory used by sets of processes. Normally, one would not expect that memory used by one group would be charged to another but, as Shakeel Butt described in a memory-management track session at the 2019 Linux Storage, Filesystem, and Memory-Management Summit, that does happen in a number of different situations. It's often a problem, but occasionally it's also a useful feature.

Security updates for Tuesday

Tuesday 7th of May 2019 03:23:29 PM
Security updates have been issued by Debian (389-ds-base, firefox-esr, and symfony), Fedora (poppler), SUSE (audit, ovmf, and webkit2gtk3), and Ubuntu (aria2, FFmpeg, gnome-shell, and sudo).

[$] Cleaning up after dying control groups

Tuesday 7th of May 2019 12:31:48 AM
Control groups are a useful mechanism for managing resource usage in the system, but what happens when the control groups themselves become a resource problem? In a plenary session at the 2019 Linux Storage, Filesystem, and Memory-Management Summit, Roman Gushchin described problems he has been facing with deleted control groups that take their time before actually going away. Some of these problems have been fixed, but the issue has not been truly resolved.

[$] Proactively reclaiming idle memory

Tuesday 7th of May 2019 12:30:21 AM
Shakeel Butt started his 2019 Linux Storage, Filesystem, and Memory-Management Summit session by noting that memory makes up a big part of the total cost of equipping a data center. As a result, data-center operators try to make the best use of memory they can, generally overcommitting it significantly. In this session, Butt described a scheme in use at Google to try to improve memory utilization; while the need for the described functionality was generally agreed upon, the developers in the room were not entirely happy with the solution presented.

[$] Improving fget() performance

Monday 6th of May 2019 08:24:40 PM

The performance of the fget() function in the kernel was the topic of a discussion led by Dave Watson at the 2019 Linux Storage, Filesystem, and Memory-Management Summit (LSFMM). fget() is used to take a reference to a file (i.e. bump a reference count), based on its file descriptor, and to return the struct file pointer for it; references are dropped with fput(). Some recent profiling at Watson's employer, Facebook, found the function to be taking a sizable portion of the CPU time for some applications, so he wanted to talk about some of the things he has tried to make that situation better.

[$] Issues around discard

Monday 6th of May 2019 05:47:22 PM

In a combined filesystem and storage session at the 2019 Linux Storage, Filesystem, and Memory-Management Summit (LSFMM), Dennis Zhou wanted to talk about discard, which is the process of sending commands (e.g. TRIM) to block devices to indicate blocks that are no longer in use. Discard is a "serious black box", he said; it is a third way to interact with a drive, but Linux developers have no real insight into what its actual effects will be. That can lead to performance and other problems.

[$] NUMA nodes for persistent-memory management

Monday 6th of May 2019 05:20:50 PM
While persistent memory is normally valued for its persistence, there is also a subcurrent of interest in using it in settings where persistence is not important. In particular, the fact that this memory is relatively inexpensive makes it appealing to use instead of ordinary RAM in budget-conscious settings. At the 2019 Linux Storage, Filesystem, and Memory-Management Summit, two sessions in the memory-management track looked at how the kernel's NUMA mechanism could be pressed into service to manage non-persistent uses of persistent memory.

[$] Transparent huge pages, NUMA locality, and performance regressions

Monday 6th of May 2019 05:15:54 PM
Sometimes, the kernel's no-regression rule may not have the desired result. Andrea Arcangeli led a session at the 2019 Linux Storage, Filesystem, and Memory-Management Summit to make the point that the recent reversion of a fix after a performance regression was reported has led to worse performance overall — with, as is his wont, a lot of technical information to back up that point. With a wider understanding of what is at stake here, he hopes, the reversion can itself be reverted.

Security updates for Monday

Monday 6th of May 2019 02:31:09 PM
Security updates have been issued by Debian (jquery, librecad, and phpbb3), Fedora (bubblewrap, java-11-openjdk, libvirt, openssh, and pacemaker), Mageia (virtualbox), openSUSE (chromium, ImageMagick, and java-11-openjdk), and SUSE (openssl-1_1).

Firefox 66.0.4 released

Monday 6th of May 2019 12:45:20 PM
There is a new Firefox browser release available; its main claim to fame is that it has a fix for the certificate issue that disabled all extensions.

The 5.1 kernel has been released

Monday 6th of May 2019 01:14:46 AM
Linus has released the 5.1 kernel, right on schedule. Some of the significant changes in the release include BPF spinlocks, more year-2038 preparation, the TEO CPU-idle governor, The io_uring fast asynchronous I/O mechanism, initial support for pidfds (file descriptors that refer to a process), the SafeSetID security module, and much more. See the KernelNewbies 5.1 page for lots of details.

Yet another set of stable kernel updates

Sunday 5th of May 2019 03:50:56 PM
The 5.0.13 and 4.19.40 stable kernel updates have been released; they were originally due on May 6, but went out ahead of schedule.

More in Tux Machines

Graphics: Mesa Radeon Vulkan Driver and SPIR-V Support For OpenGL 4.6

  • Mesa Radeon Vulkan Driver Sees ~30% Performance Boost For APUs

    Mesa's RADV Radeon Vulkan driver just saw a big performance optimization land to benefit APUs like Raven Ridge and Picasso, simply systems with no dedicated video memory. The change by Feral's Alex Smith puts the uncached GTT type at a higher index than the visible vRAM type for these configurations without dedicated vRAM, namely APUs.

  • Intel Iris Gallium3D Is Close With SPIR-V Support For OpenGL 4.6

    This week saw OpenGL 4.6 support finally merged for Intel's i965 Mesa driver and will be part of the upcoming Mesa 19.2 release. Not landed yet but coming soon is the newer Intel "Iris" Gallium3D driver also seeing OpenGL 4.6 support. Iris Gallium3D has been at OpenGL 4.5 support and is quite near as well with its OpenGL 4.6 support thanks to the shared NIR support and more with the rest of the Intel open-source graphics stack. Though it's looking less likely that OpenGL 4.6 support would be back-ported to Mesa 19.2 for Iris, but we'll see.

The GPD MicroPC in 3 Minutes [Video Review]

In it I tackle the GPD MicroPC with Ubuntu MATE 19.10. I touch on the same points made in my full text review, but with the added bonus of moving images to illustrate my points, rather than words. Read more Also: WiringPi - Deprecated

today's howtos

Android Leftovers