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
-
Linux Mint 22.2 Beta Available for Testing
Some interesting new additions and improvements are coming to Linux Mint. Check out the Linux Mint 22.2 Beta to give it a test run.
-
Debian 13.0 Officially Released
After two years of development, the latest iteration of Debian is now available with plenty of under-the-hood improvements.
-
Upcoming Changes for MXLinux
MXLinux 25 has plenty in store to please all types of users.
-
A New Linux AI Assistant in Town
Newelle, a Linux AI assistant, works with different LLMs and includes document parsing and profiles.
-
Linux Kernel 6.16 Released with Minor Fixes
The latest Linux kernel doesn't really include any big-ticket features, just a lot of lines of code.
-
EU Sovereign Tech Fund Gains Traction
OpenForum Europe recently released a report regarding a sovereign tech fund with backing from several significant entities.
-
FreeBSD Promises a Full Desktop Installer
FreeBSD has lacked an option to include a full desktop environment during installation.
-
Linux Hits an Important Milestone
If you pay attention to the news in the Linux-sphere, you've probably heard that the open source operating system recently crashed through a ceiling no one thought possible.
-
Plasma Bigscreen Returns
A developer discovered that the Plasma Bigscreen feature had been sitting untouched, so he decided to do something about it.
-
CachyOS Now Lets Users Choose Their Shell
Imagine getting the opportunity to select which shell you want during the installation of your favorite Linux distribution. That's now a thing.