Windows 7 Promises Big Improvements in Battery Life
Improvements in both the Microsoft Windows 7 operating system and Intel's upcoming Westmere processors will result in significant increases in battery life, executives said in a press conference on Tuesday.
In a demonstration of two identically configured ThinkPads T400s, Intel and Microsoft claimed that a Windows XP SP2 machine consumed on average 20.2 watts, while the Windows 7 machine consumed 15.4 watts. That translated to about 1.4 hours of additional battery life, executives said.
How could an operating system make so much difference in battery life? A discussion of that point was one of the major focuses of a press conference held Tuesday in San Francisco.
The fact that the "Wintel" partners – Microsoft and Intel – work closely together is no secret; the collaboration goes back nearly 20 years, said Stephen Smith, vice president and director of Intel's Digital Enterprise Operations. And the Windows 7 partnership began the day after Windows Vista launched, joked Ruston Panabaker, the principal program manager of strategic silicon marketing.
"I can't think of another partner with the breadth of engineering engagement with Microsoft as Intel," said Mike Angiulo, general manager of Windows Planning and PC Ecosystem.
In part, that's because market share has its advantages. Part of Microsoft's extensive beta program for Windows 7 has been what it calls its "telemetry" program, where anonymous data is reported back to Microsoft about performance, the source of application and operating system crashes, and other metrics. As Intel holds close to 80 percent market share in the PC space, the amount of available data dwarfs Intel's rivals, mainly AMD. Anguilo denied, however, that any special favoritism was shown to Intel, claiming that the company's goal was to make Windows 7 work as well as possible across all platforms.
Inside its labs, Microsoft evaluates the power consumed by all parts of a hardware platform: the CPU and its bus, the memory, the storage, and other components. The same tests are run by Intel inside its own facility. The two companies can then compare notes, and, in an iterative process, move ahead on further refinements. Microsoft uses an advanced version of its Windows Performance toolkit that provided extremely fine-grained views of power states and other power and performance metrics across the processor cores.
"What we actually do with this information is tune the p-state [power state] for the Intel processors," Panabaker said.
The dramatic leap in battery life appears tied to a technology known as Windows 7 timer coalescing, a technical term for minimizing the time in which the processor enters a high-performance, full-power state. In the past, different applications have called for the processor's performance at varying times, requiring the CPU to ramp up performance and then down again, frequently. By synchronizing the timers, Intel managed to boost battery life tremendously. Intel executives said they also expect to take more advantage of this technology in future platforms.
Intel's including Clarkdale and Arrandale will launch in the fourth quarter, about the time that Microsoft launches Windows 7 on Oct. 22. Intel showed off an Arrandale chip running Windows 7 and a two video windows as a demonstration of its stability.
Internal tests running on a 2.53-MHz Penryn chip on top of a Cantiga-GM (B2) chipset showed that Intel recorded a 2.8 percent improvement in idle power using Windows 7 versus Windows Vista SP2, and an 11 percent improvement when playing back a standard-definition DVD (18.35 watts versus 16.53 watts).
Intel's Westmere platforms also include AES hardware acceleration, a technology to improve the performance of the AES algorithm used in encryption, such as Microsoft's BitLocker full-disk-encryption technology.
An AMD spokesman confirmed that AMD will offer both of these technologies inside its own microprocessors as well.
Editor's Note: This story was updated at 2:20 PM PDT with additional details from the press conference and comments from AMD.