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 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.