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Red Hat Gets the Green Light as ‘Greenest’ Operating System

The environment and green issues have become pervasive across all facets of life. Everyone is keen to ‘go green’ whether it’s cutting down on water usage, recycling, driving a hybrid car or any number of other initiatives. It’s no different at Red Hat, where we are working hard to deliver greener products and solutions. A recent Network World test examining power consumption to determine the ‘greener’ operating system validates Red Hat’s efforts to move toward green computing.

Network World ran multiple power consumption tests using Red Hat Enterprise Linux 5.1, SUSE Enterprise Linux 10 SP1 and Windows Server 2008 Enterprise Edition on servers from Dell, IBM and HP. Red Hat Enterprise Linux ranked at the top in keeping the power draw in check, pulling as much as 12 percent less power than Windows 2008 on identical hardware. This reduced power draw was evident across testing in both performance and power saving modes and transcended all server models used in the test bed.



Red Hat is significantly involved in the development of projects that are focused on saving power. Many provide benefits for customers today–as shown by the Network World report–while others aim to provide even greater benefits in the future. Example efforts include:

  • We’re a contributing member to www.LessWatts.org, an Intel-sponsored project bringing together developers, users and sysadmins all in the effort to create a community around saving power on Linux.
  • One of several interesting projects that are part of the LessWatts program is PowerTOP, a Linux tool that helps identify programs that are power-hungry while a system is idle. It allows us to measure the power use by individual applications and then optimize those that have poor power footprints. For example, we are steadily working on server applications in an effort to identify power inefficient algorithms (such as polling-based rather than event-based). These are being modified (usually) to event based algorithms, using HAL-based notifications if necessary. PowerTOP technology is also being applied to the kernel itself, where there is ongoing auditing work to find pollers. The end result is a more efficient kernel. We have been doing this work for the past year or so and it has accumulated to the point where we are seeing meaningful power savings. And, of course, work in this area is still ongoing.
  • Another interesting area of development concerns support for CPU clock frequency scaling. Clock scaling allows us to change the clock speed of a running CPU on the fly. Customers are already seeing the results of this work: in Red Hat Enterprise Linux 5.2 we added support for Intel’s Dynamic Acceleration Technology, which provides power saving by quiescing idle CPU cores, and also offers performance gains by potentially overclocking busy cores within safe thermal levels.
  • Red Hat worked close with AMD to prove support for PowerNow! – a technology for power management.
  • It is always worth mentioning that virtualization, which is included in all Red Hat Enterprise Linux products, provides many power benefits from consolidation to resource management.
  • Also in the virtualization arena, Red Hat is busy working on para-virtualized device drivers for Windows guests – which should improve guest performance by eliminating the existing high-overhead drivers, with obvious power efficiency improvements. Para-virtualized drivers for fully virtualized Red Hat Enterprise Linux guests were released last month.
  • There is also ongoing work in Red Hat and the community to improve laptop power usage, which indirectly impacts overall power consumption. Examples are suspend/resume/hibernate work, and features such as automatic screen backlight intensity reduction as a laptop becomes idle.
  • The new tickless kernel is provided in Fedora 9 and likely to move to Red Hat Enterprise Linux in the future. Red Hat has been a key developer of this technology, which allows the kernel to properly idle itself when appropriate. Today the kernel tick-rate is 1000/second so it is hard to really quiesce it. The tickless kernel sets system into a low-power state based on knowledge of future timer-based events. Long (multi-second) idle periods are possible.

Our efforts around cloud computing also hold a place in making datacenters more environmentally friendly. Companies don’t have to host their own machines when they need extra compute space, eliminating the need to have the extra energy and materials on hand that could lead to environmental waste. In addition, Red Hat Enterprise Linux and Fedora have less hardware requirements, making it possible for people around the world to use legacy hardware while still getting the same functionality.

We continue to make green computing a company-wide effort and continuously examine power management features that can be implemented in Red Hat Enterprise Linux.

As the saying goes, “it ain’t easy being green.” But at Red Hat, we’re putting our best foot forward in an effort to reduce our carbon footprint on the earth.