Unless you're using a really old machine or cheap netbook, almost any system you touch with Linux these days is going to be a multiprocessor system. Any server machine deployed within the past five years should have at least two CPUs, and most desktops released in the past three years have at least two cores. For a number of reasons, you might want to "pin" some tasks so they run exclusively on a single CPU or set of CPUs.
Whether you want to ensure resources for a process, ensure that a process doesn't hog all system resources or improve a process that doesn't scale well to multiple CPUs, you can use
taskset to assign a task to specific CPUs. It's pretty simple.
taskset, you "bond" a process to a CPU. Let's say you want to run Google Chrome on one CPU. You'd run something like this:
taskset 0x00000001 google-chrome
Now Chrome will be limited to CPU 0 (0x00000001 is the "mask" for CPU 0). If you wanted to assign it to two CPUs, you would use
taskset 0x00000003 instead. Or you could use the
-c option and specify the CPUs by numerical ranges. See the taskset man page for more on that.
To see what processors a task is assigned to, try running
taskset -p XXXX, where XXXX is the process ID (PID). If you're on a two-core system, for example, and haven't set the affinity, it will return 3. If you've assigned it to both cores/CPUs, then it will return 3. I don't make the syntax, I just write about it ...
Is this going to speed up your system or be worth doing with all tasks? Nope. It is, however, something you can try to experiment with when you're having performance problems or having issues with a process/application causing problems with the rest of the system. I'd recommend testing it out on your desktop or test systems before attempting it in a production environment -- but with the right combination, you might be able to solve some system problems in short order.
Joe 'Zonker' Brockmeier is a freelance writer and editor with more than 10 years covering IT. Formerly the openSUSE Community Manager for Novell, Brockmeier has written for Linux Magazine, Sys Admin, Linux Pro Magazine, IBM developerWorks, Linux.com, CIO.com, Linux Weekly News, ZDNet, and many other publications. You can reach Zonker at email@example.com and follow him on Twitter.