Server NewsLinux 3.9 Clamps Down on Power, Speeds Up with SSDs

Linux 3.9 Clamps Down on Power, Speeds Up with SSDs

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Linus Torvalds is now releasing the second major new Linux kernel milestone of 2013. The Linux 3.9 kernel includes new features that will make the open source operating system faster and more efficient than ever before.

The 3.9 kernel follows the previous Linux 3.8 kernel by just 10 weeks and after eight release candidates.

“Whatever the reason, this week has been very quiet, which makes me much more comfortable doing the final 3.9 release, so I guess the last -rc8 ended up working,” Torvalds wrote in a mailing list message. “Because not only aren’t there very many commits here, even the ones that made it really are tiny and pretty obscure and not very interesting.”


One of the new capabilities landing in the Linux 3.9 kernel is PowerClamp, which has been developed by Intel. The basic idea behind PowerClamp is to enable a new level of power control and server operations efficiency.

Linux 3.9 Kernel“On Intel CPUs, C-states provide effective power reduction, but so far they’re only used opportunistically, based on workload,” Intel’s PowerClamp documentation states. “With the development of the intel_powerclamp driver, the method of synchronizing idle injection across all online CPU threads was introduced. The goal is to achieve forced and controllable C-state residency.”

SSD Caching

The Linux 3.9 kernel will also continue to extend Linux’s SSD capabilities. Red Hat developers have contributed a new feature that will enable SSD caching to speed up server operations. The feature adds a cache target to the Linux device mapper.

“Add a target that allows a fast device such as an SSD to be used as a cache for a slower device such as a disk,” Red Hat developer Joe Thornber wrote in his Linux kernel commit message. “A plug-in architecture was chosen so that the decisions about which data to migrate and when are delegated to interchangeable tunable policy modules.”


Linux has been steadily improving ARM architecture support in recent releases. The Linux 3.7 release, which debuted in December of 2012, was the first to unify ARM support in Linux.

With the 3.9 kernel, support for the KVM virtualization hypervisor is now coming to ARM too. The initial KVM support in Linux is specifically for ARM Cortex A-15 processors.

Sean Michael Kerner is a senior editor at ServerWatch and, the news service of the IT Business Edge Network, the network for technology professionals. Follow him on Twitter @TechJournalist.

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