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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 15 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.

[$] Minimizing the use of tail pages

Saturday 4th of May 2019 03:32:17 PM
Compound pages are created by the kernel as a way of combining a number of small pages into a single, larger unit. Such pages are implemented as a single "head page" at the beginning, followed by a number of "tail pages". Matthew Wilcox has concluded that it would be beneficial to minimize the use of tail pages in the kernel; he ran a session during the memory-management track at the 2019 Linux Storage, Filesystem, and Memory-Management Summit to explore how that could be done. The discussion ranged widely, veering into the representation of DMA I/O operations, but few hard conclusions were reached.

[$] The search for available page flags

Saturday 4th of May 2019 03:31:52 PM
Among the many other things crammed into the page structure that is used to represent a page of memory in the kernel is a set of flags to track the state of the page. These flags have been in short supply for some time; LWN looked at the problem nearly ten years ago. Jérôme Glisse ran a session during the memory-management track of the 2019 Linux Storage, Filesystem, and Memory-Management Summit to explore ways of making some flags available for new uses. While there may be some easily available bits in the field that holds the page flags, obtaining a significant number of them may be tricky.

More stable kernel updates

Saturday 4th of May 2019 01:20:21 PM
The 5.0.12, 4.19.39, 4.14.116, and 4.9.173 stable kernel updates have been released; each contains another set of important fixes.

Firefox bug disables all extensions

Saturday 4th of May 2019 01:01:17 PM
The expiration of the extension signing certificate has evidently caused all extensions to be disabled, leading to a fair amount of discomfort on the net. There is evidently a fix being rolled out, but it requires that the "Studies" mechanism be enabled in the privacy preferences. Meanwhile, the best short-term approach seems to be to avoid restarting Firefox if possible.

More in Tux Machines

Android Leftovers

Xfce 4.14 Lands in Tumbleweed

Ahoy! openSUSE Xfce team is pleased to announce that the long awaited Xfce 4.14 has been released for Tumbleweed. After a long development cycle (4 years!), all of the core components and applications have been ported to GTK 3. Among the main new features and improvements, the xfwm4 window manager has finally gained support for VSync, HiDPI, hardware GLX and various compositor improvements. You can check out the neat new features in the official Xfce 4.14 tour and the official release announcement. Read more

today's howtos

Wine 4.0.2 Released

  • Wine Announcement

    The Wine maintenance release 4.0.2 is now available.

  • Wine 4.0.2 Released With 66 Bug Fixes

    Wine 4.0.2 is out today as the second stable point release to this year's Wine 4.0 cycle. As is customary for Wine stable point releases, only bug fixes are allowed in while new features come by way of the bi-weekly development releases that will lead up to the Wine 5.0 release in early 2020.

  • The stable Wine 4.0.2 release is now available

    If you prefer to walk on the calmer side of life, the Wine 4.0.2 release has been made available today. As it's just a "maintenance" release, there's no big new features which are reserved for the current 4.xx series currently at 4.14 released on August 17th. With that in mind they noted 66 bugs being marked as solved. These bugs include issues with Worms 2, Warframe, Rogue Squadron 3D, Settlers III, Mass Effect, F.E.A.R. 2: Project Origin, The Sims and plenty more.

  • Linux Gaming FINALLY Doesn't SUCK!