LessWatts at Debconf8

I’m in Mar del Plata, Argentina, for the 8th Debconf, and just finished my talk.

First of all, I’ve heard about the special dedication the organization team put together before I got here, and I have to say it is really “putting a smile on your face“. There are small thoughtful details adding to the content: the bot in the irc.oftc.net#debconf saying who just arrived, what is the next talk, when the dinner is served; a souvenir and local guide in English – Super Cow Powers include – with some cultural and historical facts, places to go around, what to eat, some phrases in Spanish to help, and such. The streaming seems perfect, several volunteers and the people attending it demonstrate their appreciation to the organization and also help to keep the silence in the quite hacklab – right next to the video-audio station.

I talked about LessWatts, a project around many efforts and initiatives around power consumption in Linux. A year ago, when the project was launched, PowerTop was the tool and some documentation. It is impressive how much the project grew in just one year, how many other tools where added: BLTK(Battery Life Tookit), PPM(Power Policy Management) and others, and many many guides, documentation, tricks for development. Like:

• Polling Avoid frequent, unnecessary polling
• Race to Idle Save power by running at the highest speed
  Processors tend to be so good at saving power during idle, that often it’s better to go as fast as possible so that you can then be idle longer.
• Turn devices off Open devices can prevent the system from entering power saving state
• Group Timers Many programs use times, so group them to reduce idle wakeups.
• Use large buffers Media playback requires a large buffer, large enough for a minute of audio or 20 minutes of video.
• Optimize Sleep Duty Cycle It matters how frequently you go in and out of idle. Stay in idle for long periods of time. Avoid interrupting idle as much as possible.
• Beware of high level languages High level languages are convenient tools to achieve results quickly and often have features to do complex things with minimal effort. However, be aware that some of these contructs are hard to implement and sometimes the runtime environment that implements the high level language does so using polling at a high frequency. When using high level languages such as Java*, Visual C#*, Python*, and Ruby, check the end result and try to avoid some of the more complex threading primitives. In addition, where you have a choice of runtime environment provider, evaluate different alternatives and versions.

There were some questions, which I was glad because I spoke too fast and were expecting more questions as I finished before I should. I was glad to see some developers asking for people to adopt PowerTop and BLTK as packages for Debian, everybody downloading, testing and some funny comments: “Now I will harm the environment again by opening my Firefox”. Of course, many “I would love my battery last longer”. Some nice ideas about areas to be researched and focus: swapping, booting, memory. The video for the talk will be available soon. And the always happy moment of giving t-shirts Funny coincidence, this was a special batch from the t-shirts we are doing at Intel for giving to people in conferences, and for my surprise this new ts provider uses the same logo as Debian.

I’m really glad I’ve came, and I think my difficult relationship with Debian may improving. Now I can just relax and enjoy my friends. I will post some pictures later.

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