Keeping Hot Chips Cool Thermal Management for Green Computing Yang Ge Professor Qinru Qiu

utline Background Background – Need for green computing – Adverse effects of high temperature – Thermal management techniques Ongoing project Ongoing project – Power and thermal management for single chip cloud computer (SCC)

The need for green computing Computers consume 3% of US energy use Computers consume 3% of US energy use – Saving 1% of energy of data center is more than saving a power plant Each computer generates 1 ton of CO 2 every year Each computer generates 1 ton of CO 2 every year – Equivalent to the CO 2 emission of a car driving a round trip between New York and Los Angeles

Power and Cost for Cooling Systems The energy dissipation for cooling system is high The energy dissipation for cooling system is high – Cooling fan power can reach up to 51% of the overall server power budget The cooling cost is expensive in large data centers The cooling cost is expensive in large data centers – The total cooling costs for large data centers can run into tens of millions of dollars Fans 51% Mem 20% CPU 24% Other 6% IBM P670 Server power breakdown

Adverse effects of high temperature to VLSI Chips Affects the system reliability and causes permanent device failure Affects the system reliability and causes permanent device failure Doubles leakage power consumption every 9 o C increase Doubles leakage power consumption every 9 o C increase Requires to increase fan speed which could reduce fan life time Requires to increase fan speed which could reduce fan life time

Thermal Management Techniques Offline Techniques Online Techniques Temperature aware scheduling Dynamic voltage frequency scaling Temperature aware task migration

Ongoing Project Power and thermal management for single chip cloud computer (SCC) Power and thermal management for single chip cloud computer (SCC)

24 tiles arranged in 6X4 arrays 24 tiles arranged in 6X4 arrays 2 CPUs on each tile 2 CPUs on each tile A router associated with each tile A router associated with each tile 4 memory controllers go to on board memory 4 memory controllers go to on board memory Overview of SCC Architecture

SCC and MCPC communicates over PCIe bus SCC and MCPC communicates over PCIe bus MCPC runs Ubuntu x64 and SW from Intel MCPC runs Ubuntu x64 and SW from Intel Load Linux image on each core Load Linux image on each core read and modify SCC registers read and modify SCC registers Load programs on the SCC cores. Load programs on the SCC cores. Management Console PC (MCPC)

6 voltage domains 6 voltage domains 24 Frequency domains, one for each tile 24 Frequency domains, one for each tile 2 temperature sensors on each tile 2 temperature sensors on each tile Voltage and frequency can be changed separately on each domain Voltage and frequency can be changed separately on each domain Power and Thermal Management

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