Google spanks memory, disk and networking vendors
Calls for proportional response
"A processor running at a lower voltage-frequency mode can still execute instructions without requiring a performance-impacting mode transition," the Googlers write. "It is still active. There are no other components in the system with active low-power modes. Networking equipment rarely offers any low-power modes, and the only low-power modes currently available in mainstream DRAM and disks are fully inactive. That is, using the device requires paying a latency and energy penalty for an inactive-to-active mode transition. Such penalties can significantly degrade the performance of systems idle only at submillisecond time scales."
Turning from low power states, Barroso and Hólzle look at the average usage and peak usage of servers. The problem here is that servers show the most energy efficiency under peak usage but sadly spend very little time operating all out. In the average 10-50 per cent usage zone, servers demonstrate only between 20 and 70 per cent energy efficiency.
So, the Googlers have called on hardware designers to produce gear which can hit between 60 and 90 per cent energy efficiency when running in the average usage zone. You can see the idealized curve for such a scenario here.
Reaching this dream state will take work from all parts of the hardware industry, according to Barroso and Hólzle.
"Energy-proportional computers would enable large additional energy savings, potentially doubling the efficiency of a typical server," they write. "Some CPUs already exhibit reasonably energy-proportional profiles, but most other server components do not.
"We need significant improvements in memory and disk subsystems, as these components are responsible for an increasing fraction of the system energy usage. Developers should make better energy proportionality a primary design objective for future components and systems. To this end, we urge energy-efficiency benchmark developers to report measurements at nonpeak activity levels for a more complete characterization of a system's energy behavior."
Google takes its data center research very seriously, and hardware makers should pay attention to the results.
As you all know, Google makes its own servers, hoping to achieve cost and energy efficiency gains. In addition, the company crafts its own switches for similar reasons. (Our congratulations go out again to Nyquist Capital analyst Andrew Schmitt for his investigative work here. We understand a report is coming out soon noting that Steve Jobs has a large ego.)
While Google's rivals appear unwilling to do similar custom work, they will demand that hardware makers produce gear with comparable cost/energy efficiency characteristics in order to remain competitive with the ad broker. Beyond that, any lost opportunity to meet Google's standards means that a component maker faces the proposition of missing out on huge volume sales to Google.
Overall, the work of Barroso and his peers at Google is a huge help to server customers of all shapes and sizes. Google may have unique needs from a scale perspective, but its heft is pushing hardware makers in an energy conscious direction that threatens to benefit data center operators as a whole. ®
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