SAN DIEGO, CA – Computer scientists at UC San Diego and Microsoft Research have created a plug-and-play hardware prototype for PCs that induces a new energy saving state known as “sleep talking.”
The new mode falls between awake mode and sleep mode, and is designed to provide some of the energy savings of sleep mode combined with the network-and-internet-connected convenience of awake mode.
UC San Diego computer science PhD student Yuvraj Agarwal presented a paper on the prototype at the USENIX Symposium on Networked Systems Design and Implementation.
“Large numbers of people keep their PCs in awake mode even though the PCs are relatively idle for long blocks of time because they want to stay connected to an internal network, or the internet or both,” said Agarwal. “I realized that most of the tasks that people keep their computers on for — like ensuring remote access and availability for virus scans and backup, maintaining presence on instant messaging (IM) networks, being available for incoming voice-over-IP (VoIP) calls, and file sharing and downloading — can be achieved at much lower power-use levels than regular awake mode,” said Agarwal.
The USB-connected hardware and software plug-in system allows a PC to remain in sleep mode while continuing to maintain network presence and run well-defined application functions. It supports instant messaging applications, VoIP, large background web downloads, peer-to-peer file sharing networks such as BitTorrent, and remote access. The computer scientists say their system is easily extensible to support other applications.
The goal of the new device – dubbed Somniloquy – is to encourage people to put their PCs in sleep mode more often, for example when they are not being used for computationally demanding tasks. “Reducing energy consumed by wall-powered devices, especially computing equipment, offers a huge opportunity to save money and reduce greenhouse gases,” said Agarwal.
Somniloquy’s low-power secondary processor functions at the PC’s network interface. It runs an embedded operating system and impersonates the sleeping PC to other hosts on the network. Somniloquy will wake up the PC over the USB bus if necessary. For example, during a movie download, when the flash memory fills up, Somniloquy will wake up the PC and transfer the data. When the transfer is complete, it will go back to sleep mode and Somniloquy will again impersonate the computer on the network.
The current prototypes work for desktops and laptops, over wired and wireless networks, and are incrementally deployable on systems with an existing network interface. It does not require any changes to the operating system on the PC, to routers or other network infrastructure, or to remote application servers.
The researchers evaluated Somniloquy in various settings and say that it consumes 11 to 24 times less power than a PC in idle state, which could translate to energy savings of 60 to 80 percent depending on their use model.
In the future, Somniloquy could be incorporated into the network interface card of new PCs, which would eliminate the need for the prototype’s external USB plug-in hardware.