Optimization
maddog's Doghouse
Understanding how optimization works is just as crucial to fast code as a good compiler.
I have written about the importance of knowing how things work "from the bottom up." Usually, this includes understanding (at least at an overall level) how the hardware works and how compilers and operating systems accomplish their tasks.
Recently a university student I know was taking a course on embedded systems, and they were writing a device handler in the C language. The student had defined a global variable to hold a value that would be filled in by the hardware itself, and not initialized by any other statement. Their professor told them that they had to declare the variable "volatile," or else the compiler might "optimize" the variable outside of the scope of the module. From the code the compiler could "see," there was no way that the variable's value would change, so normal optimizations might assume that the value in the variable was the same as the first time it was set, and that registers loaded with the contents of that variable would still be valid.
Wrong.
[...]
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 Kernel 6.16 Reaches EOL
Linux kernel 6.16 has reached its end of life, which means you'll need to upgrade to the next stable release, Linux kernel 6.17.
-
Amazon Ditches Android for a Linux-Based OS
Amazon has migrated from Android to the Linux-based Vega OS for its Fire TV.
-
Cairo Dock 3.6 Now Available for More Compositors
If you're a fan of third-party desktop docks, then the latest release of Cairo Dock with Wayland support is for you.
-
System76 Unleashes Pop!_OS 24.04 Beta
System76's first beta of Pop!_OS 24.04 is an impressive feat.
-
Linux Kernel 6.17 is Available
Linus Torvalds has announced that the latest kernel has been released with plenty of core improvements and even more hardware support.
-
Kali Linux 2025.3 Released with New Hacking Tools
If you're a Kali Linux fan, you'll be glad to know that the third release of this famous pen-testing distribution is now available with updates for key components.
-
Zorin OS 18 Beta Available for Testing
The latest release from the team behind Zorin OS is ready for public testing, and it includes plenty of improvements to make it more powerful, user-friendly, and productive.
-
Fedora Linux 43 Beta Now Available for Testing
Fedora Linux 43 Beta ships with Gnome 49 and KDE Plasma 6.4 (and other goodies).
-
USB4 Maintainer Leaves Intel
Michael Jamet, one of the primary maintainers of USB4 and Thunderbolt drivers, has left Intel, leaving a gaping hole for the Linux community to deal with.
-
Budgie 10.9.3 Now Available
The latest version of this elegant and configurable Linux desktop aligns with changes in Gnome 49.