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The Problem of Power Consumption in Servers

L. Minas and B. Ellison

Intel-Lab

In Dr. Dobb’s Journal, May 2009Prepared and presented by Yan Cai

Fall 2009 Green Computing

Motivation

• Server energy consumption has increased from 50w to 250w since 2000

• Energy cost will exceed the server cost if this trend does not change

2Source: IDC, Scaramella 2006

Outline

• Motivation• Where heat comes from• How cooling is achieved• How power is consumed• Conclusions

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Where heat comes from

• Server form factor

• Server power consumption is affected by server form factor, including the individual configuration, the heat and thermal environment the workload being processed …

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Server form factor

Pedestal servers

2U rack servers

1U rack servers

Blade servers

1U

Pedestal2U

Blade

Where heat comes from

• The amount of heat, (Q), generated by an integrated circuit is a function of The efficiency of the components' design (e) The technology used in its manufacturing process (t) The frequency and voltage at which it operates (f,v)

• Over-clocking also generates a great amount of heat

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),,,( vfteFQ

Outline

• Motivation• Where heat comes from• How cooling is achieved• How power is consumed• Conclusions

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How cooling is achieved

• Two common methods Heat sinks Fans

7Natural convection heat sink (Source: Wikipedia, 2008)

Outline

• Motivation• Where heat comes from• How cooling is achieved• How power is consumed• Conclusions

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How power is consumed

Servers Cost # of Processors

Volume $25,000 1 ~ 2

Mid-range $25,000 ~ $499,999 2 ~ 4

High-end ≥ $500,000 ≥ 8

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Estimated Average Power Use (W) per Server, by Server Class, 2000 to 2006 (Source: Koomey J 2007b Estimating Total Power Consumption by Servers in the US and the World. Oakland, CA: Analytics Press)

Estimated Average Power Use (W) per Server

Google container Data Centerhttp://www.youtube.com/watch?v=zRwPSFpLX8I

Total power consumption

• Power consumption of a Quadcore Intel Xeon server

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Server Power Consumption (Source: Intel Labs, 2008)

Total power consumption (cont’d)

• Power consumption of components

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Components Power consumption

Multi-core CPU 45 ~ 200 w

DIMM 5 ~ 21 w

Power supply efficiency loss Similar with memory p.s.

2 PCI Slots 50 w

2 ~ 4 Hard drives 24 ~ 48 w

Total power consumption (cont’d)

• Total power consumption

• Estimation of power consumption

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CPU Utilization and Power Consumption (Source: Blackburn 2008)

minminmax 100)( P

nPPPn

Memory power consumption

• The memory demand is growing in the future, because More processors on chip, Increasing use of virtualization, More memory intensive search applications (Google and Facebook)

• The memory power consumption is growing in the future The more the memories, the larger the power consumption The faster the memories, the larger the power consumption

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Memory power consumption (cont’d)

• Memory Power Comparison

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RDIMM Memory Power Comparison (Source: Intel Platform Memory Operation, 2007)

Memory power consumption (cont’d)

• Power consumption by vendors and configurations

15RDIMM Power Consumption by Vendor and Configuration (Sources: Publicly-available datasheets from each vendor, 2008)

Memory power consumption (cont’d)

• 64GB system power consumption

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Future DIMM Power Consumption by Frequency, Configuration, and Capacity (Source: Intel Platform Memory Operation, 2008)

Memory power consumption (cont’d)

• How to reduce memory energy consumption By doing thermal analysis, embedding thermal sensors and throttling

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1U Server Architecture (Source: Intel Labs, 2006)

Memory power consumption (cont’d)

• Memory throttling mechanisms Closed loop thermal throttling (CLTT)

• Closed loop, rely on thermal sensors

Open loop throughput throttling (OLTT)• Open loop, work based on bandwidth count

• Memory throttling degrades performance

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Power supply efficiency loss

• Power supply efficiency vs. utilization level

19Server Power Supply Efficiency Test Report (Source: Lawrence Berkeley National Laboratory, 2004)

Storage power consumption

• Average hard disk power consumption for average operations

• Average hard disk power consumption for IO intensive operations

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)Pr()Pr(Pr readPwritePidlePP readwriteidleaverage

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4)( readseekwriteconstant

PPPP

Conclusions

• High-end servers consume more power, but might be less efficient in terms of power consumption

• At present, CPU still consumes the most power, compared to other components

• In the future, memory can consume more power than CPU• Considering a significant amount of power loss, the efficiency of

power supplies is also very important• The power consumption by hard drives is closely related to the

workload the server is processing

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