The Linux-based Powertop energy monitoring tool is nearing a final version 2.0 release, rewritten using the Linux 2.6.36 kernel's “perf” event subsystem to offer more granular power-consumption diagnostic options. The new version is mainly developer-focused, but gains a new user interface and offers an easier way to tune a notebook's power-saving features, says the Intel-backed LessWatts.org project.

Available as beta version 1.98, Powertop 2.0 is nearing completion, according to a LessWatts.org blog post by chief developer Arjan van de Ven. The open source Powertop project was launched in 2007 as a sub-project of the Intel-backed LessWatts.org project targeting energy efficiency.

In 2008, the technology was made available by Intel-backed Moblin project, the forerunner of today's MeeGo. Designed to help developers make Intel Atom applications more power-efficient, the Powertop tool now supports ARM and UltraSPARC processor in addition to x86. 

Powertop is widely available on Linux distributions for everything from servers to devices. For example, it is used by Amazon's second-generation Kindle (pictured).

As described by Thorsten Leemhuis, writing in The H. Powertop "provides an overview of which programs engage the CPU how often and thus shorten the time the processor can remain in power-saving sleep states."

Powertop 2.0, which appeared in beta form in January, has been largely rewritten, according to van de Ven in his beta announcement (as well as a more extensive previous post from August). The developer, who was also the co-developer behind Moblin's fast-boot technology (along with Intel's Auke Kok, another Powertop contributor) explained that the tool was rewritten because the Powertop codebase had grown out of hand.

This was said to be due to the addition of numerous features to check power consumption aimed at end users. Such features have now been adopted separately by Linux distributions, so most are no longer needed in Powertop, explained van de Ven.

"With the user base moving from end users to experienced engineers, it's time for the internals of Powertop to get redone," wrote van den Ven.

Powertop 2.0's emphasis has now changed to target system diagnostics for developers. The software has been rewritten to use the Linux kernel's "perf" infrastructure, said to "give much more accurate data for the various reports," according to van de Ven. The utility now estimates power consumption by analyzing the operating environment and comparing the results with previously measured data.

New UI, more detailed reports

The new version also overhauls the user interface, and now offers a more compact overview. In addition to showing the processor load, the overview is said to indicate how often a GPU (graphics processing unit) becomes active and how often the Virtual File System (VFS) helps access storage media.

More detail is supplied about sleep periods, broken down by different cores, as well as the status of the cores, the memory controller, and I/O units, explains van de Ven. Clock speeds and shifts to turbo modes are also detailed, and another tab shows device activity overview, as well as the number of transmitted network packages.

Although the tool has shed some of its more redundant, end-user focused features, Powertop 2.0 is now said to offer an easier way to enable and disable specific power-saving features, thereby extending the battery life of notebooks.

The new version can also generate an HTML report, says van de Ven. This is said to make it easier to upload or email reports to others for fast troubleshooting.

Powertop 2.0 requires Linux 2.6.36, and some features need version 2.6.37, released in January. As Leemhuis notes, this means that the utility can for the most part only be used by Linux distributions released in the past few months.

This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.