Zack's Kernel News
Zack's Kernel News
Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.
Speeding Up Futexes…Maybe
Thomas Gleixner pointed out that the kernel's 'futex' locks used a global hash value to keep track of state changes, but that the hash values were not guaranteed to be unique. The kernel could handle these collisions, but it would slow things down. He posted a patch to provide a reference counting mechanism to allow threads to guarantee no hash collisions. He said, "this creates a futex private state that avoids hash collisions and on NUMA systems also cross-node memory accesses."
To make use of the mechanism, he said, "each thread has to attach to the futex before any other operations on that futex." He explained the usage of the sys_futex() call to increment and decrement the futex reference count.
Thomas added that, although the user interface could be simplified by having threads automatically attach to the futex, he didn't want to implement it that way. Apart from increasing memory usage, the futex attachment code would have its own performance issues if all threads on the system made use of it. As long as it was used only by threads that actually needed to avoid those hash collisions – in other words, for real-time software – the code would provide a measurable performance increase.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
TuxCare Announces Support for AlmaLinux 9.2
Thanks to TuxCare, AlmaLinux 9.2 (and soon version 9.6) now enjoys years of ongoing patching and compliance.
-
Go-Based Botnet Attacking IoT Devices
Using an SSH credential brute-force attack, the Go-based PumaBot is exploiting IoT devices everywhere.
-
Plasma 6.5 Promises Better Memory Optimization
With the stable Plasma 6.4 on the horizon, KDE has a few new tricks up its sleeve for Plasma 6.5.
-
KaOS 2025.05 Officially Qt5 Free
If you're a fan of independent Linux distributions, the team behind KaOS is proud to announce the latest iteration that includes kernel 6.14 and KDE's Plasma 6.3.5.
-
Linux Kernel 6.15 Now Available
The latest Linux kernel is now available with several new features/improvements and the usual bug fixes.
-
Microsoft Makes Surprising WSL Announcement
In a move that might surprise some users, Microsoft has made Windows Subsystem for Linux open source.
-
Red Hat Releases RHEL 10 Early
Red Hat quietly rolled out the official release of RHEL 10.0 a bit early.
-
openSUSE Joins End of 10
openSUSE has decided to not only join the End of 10 movement but it also will no longer support the Deepin Desktop Environment.
-
New Version of Flatpak Released
Flatpak 1.16.1 is now available as the latest, stable version with various improvements.
-
IBM Announces Powerhouse Linux Server
IBM has unleashed a seriously powerful Linux server with the LinuxONE Emperor 5.