Traffic Control with tc
This weekend I had an interesting dilemma. I needed to transfer about 2GB worth of data to a remote machine. That's not really a lot to download, but it can be quite a pain on an asynchronous upload home Internet connection where your upload speed is pitiful! So, I began the transfer, and wouldn't you know that halfway through, my roommate returned from work. Now, since my roommate works at a startup called Blinkx in downtown San Francisco, he has work to do pretty much 24/7. I didn't want to disturb his work, but I also didn't want to cancel my transfer. What was a hacker to do :-(
After feeling defeated for about five minutes and having no idea how to shape the current traffic connection, I stumbled onto something. tc! Yes, tc can do everything you need to shape traffic. Amazing. A little man page reading later, and in ten minutes, I was now happily transferring data and not hogging all the upload bandwidth from my roommate. Here's how I was able to limit my upload to ~30KB/sec, from our cap of ~100KB/sec.
# tc qdisc add dev eth1 root handle 1: tbf rate 300kbit burst 300kbit latency 1
Now, this command is quite a hack. I didn't actually bother to find the best options for the job, but then again, I didn't have much time. The command above merely limits the connection of my wireless device to ~30KB/sec using the Token Bucket Filter mechanism.
I highly encourage the reader to find more advanced usage of tc and craft some beautiful shaping rules. If you don't want as much control, then you may consider other useful tools such as trickle/trickled (user-space) and wondershaper. Happy hacking :-)
Practical Task Scheduling Deployment
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.
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|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- The Firebird Project's Firebird Relational Database
- Stunnel Security for Oracle
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- SUSE LLC's SUSE Manager
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Doing for User Space What We Did for Kernel Space
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