Thermal-aware Task Thermal-aware Task Placement in Data Centers Placement in Data Centers Qinghui Tang Qinghui Tang Sandeep K S Gupta Sandeep K S Gupta Georgios Varsamopoulos Georgios Varsamopoulos IMPACT Lab http://impact.asu.edu/ Arizona State University
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Thermal-aware Task Thermal-aware Task Placement in Data CentersPlacement in Data Centers
Growth Trends in data centersGrowth Trends in data centers►Power density increasesPower density increases
Circuit density Circuit density increases by a factor of 3 every 2 yearsincreases by a factor of 3 every 2 years Energy efficiency Energy efficiency increases by a factor of 2 every 2 yearsincreases by a factor of 2 every 2 years Effective power density Effective power density increases by a factor of 1.5 every 2 yearsincreases by a factor of 1.5 every 2 years
[Keneth Brill: The Invisible Crisis in the Data Center][Keneth Brill: The Invisible Crisis in the Data Center]
►Maintenance/TCO risingMaintenance/TCO rising Data Center TCO doubles every three yearsData Center TCO doubles every three years By 2009, the three-year cost of electricity will exceed the purchase By 2009, the three-year cost of electricity will exceed the purchase
cost of the servercost of the server Virtualization/Consolidation is a 1-time/short term solutionVirtualization/Consolidation is a 1-time/short term solution
[Uptime Institute][Uptime Institute]
►Thermal management corresponds to an increasing portion Thermal management corresponds to an increasing portion of expensesof expenses Thermal-aware solutions becoming prominentThermal-aware solutions becoming prominent Increasing need for thermal awarenessIncreasing need for thermal awareness
Thermal-awareThermal-awareTask Placement ProblemTask Placement Problem
Given an incoming task, find a task partitioning and Given an incoming task, find a task partitioning and placement of subtasks to minimize the (increase of) placement of subtasks to minimize the (increase of) peak inlet temperaturepeak inlet temperature
= + ×
inlettemperatures
supplied airtemperatures
heat distributionutilization
vector
Tin Tsup D U
(a + )
bbbbbbb
XInt AlgorithmApproximation solution(genetic algorithm)►Take a feasible solution
and perform mutations until certain number of iterations
Assigning tasks in a way that tries to Assigning tasks in a way that tries to achieve uniform outlet temperature achieve uniform outlet temperature distributiondistribution
Assigning more task to nodes with low Assigning more task to nodes with low inlet temperature (water filling process)inlet temperature (water filling process)
► Minimum computing energyMinimum computing energy Assigning tasks in a way that keeps the Assigning tasks in a way that keeps the
number of active (power-on) chassis as number of active (power-on) chassis as few as possiblefew as possible
Server with coolest inlet temperature firstServer with coolest inlet temperature first► Uniform Task (UT)Uniform Task (UT)
Assigning all chassis the same amount of Assigning all chassis the same amount of tasks (power consumptions)tasks (power consumptions)
All nodes experience the same power All nodes experience the same power consumption and temperature riseconsumption and temperature rise
Performance ResultsPerformance Results► Xint outperforms other algorithmsXint outperforms other algorithms► Data Centers almost never run at 100%Data Centers almost never run at 100%
Plenty of room for benefits!Plenty of room for benefits!
Performance ResultsPerformance Results► Xint outperforms other algorithmsXint outperforms other algorithms► Data Centers almost never run at 100%Data Centers almost never run at 100%
Plenty of room for benefits!Plenty of room for benefits!
►Thermal-aware task placement can Thermal-aware task placement can significantly reduce heat recirculationsignificantly reduce heat recirculation XInt performance thrives at around 50% CPU XInt performance thrives at around 50% CPU
utilizationutilization►Not much can be done at 100% utilizationNot much can be done at 100% utilization
Cooling savings can exceed 30%Cooling savings can exceed 30%(in comparison to other schemes)(in comparison to other schemes)
►Cost of operation reduces by 15%Cost of operation reduces by 15%(if initially 1:1 ratio of computing-2-cooling)(if initially 1:1 ratio of computing-2-cooling)
► HPC model in mindHPC model in mind Long-running jobs (finish time is the same Long-running jobs (finish time is the same —— infinity) infinity)
► One-time arrival (starting time is the same)One-time arrival (starting time is the same)► Utilization homogeneityUtilization homogeneity
(same utilization throughout task’s length)(same utilization throughout task’s length)► Non preemptive/movable tasksNon preemptive/movable tasks► Data Center equipment homogeneityData Center equipment homogeneity
power consumptionpower consumption computational capabilitycomputational capability
► Cooling is self-controlledCooling is self-controlled
Recirculation coefficients:Recirculation coefficients:a fast thermal modela fast thermal model
► Reduce/Simplify the Reduce/Simplify the “thermal map” “thermal map” concept to points of concept to points of interest: equipment interest: equipment air inletsair inlets
► Can be computed Can be computed from CFD from CFD models/simulationsmodels/simulations
Matrix Aaij: portion of heatexhausted from node ithat directly goes to node j
Opportunities & Challenges► Data centers don’t run at fulll
unitilization Can choose among multiple CPUs
to allocate a job Different thermal impact per CPU
► Need for fast thermal evaluation► Temporal and spatial
Heterogeneity of Data Centers In equipment In workload
Thermal issues► Heat recirculation
Increases as equipment density exceeds cooling capacity as planned
► Hot spots Effect of Heat Recirculation
► Impact:Cooling has to be set low enoughto have all inlet temperatures insafe operating range
Data Center Thermal ManagementData Center Thermal ManagementIncreasing need for thermal awarenessIncreasing need for thermal awareness
► Power density increasesPower density increases Circuit density Circuit density increases by a factor of 3 every increases by a factor of 3 every
2 years2 years Energy efficiency Energy efficiency increases by a factor of 2 increases by a factor of 2
every 2 yearsevery 2 years Effective power density Effective power density increases by a factor increases by a factor
of 1.5 every 2 yearsof 1.5 every 2 years[Keneth Brill: The Invisible Crisis in the Data Center][Keneth Brill: The Invisible Crisis in the Data Center]
► Maintenance/TCO risingMaintenance/TCO rising Data Center TCO doubles every three yearsData Center TCO doubles every three years By 2009, the three-year cost of electricity will By 2009, the three-year cost of electricity will
exceed the purchase cost of the serverexceed the purchase cost of the server Virtualization/Consolidation is a 1-time/short term Virtualization/Consolidation is a 1-time/short term
solutionsolution► Thermal management corresponds to an Thermal management corresponds to an
increasing portion of expensesincreasing portion of expenses Thermal-aware solutions becoming prominentThermal-aware solutions becoming prominent
IC Case/chassis room
firmware
O/S
Application
(middleware)
Dynamic voltage scalingDynamic frequency scalingCircuitry redundancy
Fan speed scaling
CPU Load balancing
Thermal-aware VM
Data centerjob scheduling
softwaredimension
physicaldimension
Thermal-aware solutionsat various levels
A dynamic thermal-A dynamic thermal-aware control platform aware control platform is necessary for online is necessary for online thermal evaluationthermal evaluation
Results(1)Results(1)►Recirculation Coefficients Consistent with datacenter observations Large values are observed along diagonal Strong recirculation among neighboring servers, or between