Auto-loading Kernel Modules
When configuring your system, at first you may think it would be best to compile everything as a module. This isn't always a good idea, as it won't always save memory. Each module uses memory in 4K pages, so the last page will generally have some space wasted. Therefore, if you'll almost always have the module in use, you might as well compile it into the kernel. Also, keep in mind that kerneld itself consumes some memory (in my experience, at least 12 pages), so if you only have a few small modules to worry about, it would be better to compile them into the kernel or load them explicitly in the startup script.
Modules for file systems must be loaded as long as the file system is mounted, even if you're not using it. So if you keep /dos mounted all the time, don't bother to compile support for FAT as a module. If you don't like that option, you could look into using an automount daemon instead of keeping the file system mounted.
Be careful with modules that include information that may be changed when run. For example, the sound driver keeps track of the volume, and if you compile it as a module, the volume will be reset to the default each time it is loaded.
Finally, be careful not to compile something as a module if it will be used at boot time before kerneld is started. This includes the root file system, of course. For many systems, you'll find that you need both ELF and a.out support before kerneld starts. You may be able to overcome some problems by installing kerneld as one of the first programs executed by the startup scripts, but be careful if you're also doing dial-on-demand, as you may have something like sendmail in your startup scripts that will trigger it. As long as you have your old kernel around as a safety net, though, feel free to experiment.
Preston Crow Preston Crow is a graduate student in computer science at Dartmouth College. He became a happy Linux user in the summer of 1995, shortly before becoming happily married.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Doing for User Space What We Did for Kernel Space
- Tech Tip: Really Simple HTTP Server with Python
- SuperTuxKart 0.9.2 Released
- Rogue Wave Software's Zend Server
- Parsing an RSS News Feed with a Bash Script
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide