CSE 691: Energy-Efficient ComputingLecture 5

SPEED: processorAnshul Gandhi

1307, CS buildinganshul@cs.stonybrook.edu

opt_allocation paper

3

U.S. Data Center Energy Consumption

2000 2006 20110

102030405060708090

100

$ 8.4 billion

kWh

(in b

illio

ns)

120 billion kWh

12 billion kWh

50 billion kWh

Source: EPA report to Congress on Server and Data Center Energy Efficiency ,2007

4

P

Get the best performance from thepower, P, that we have.

Goal

Data Center

5

PP1

P2

P3

Goal How to split P to minimize mean response time?

Right answer can improve performance by up to 5X

Constraint:P ≥ P1 + P2 + P3

6

Our Experimental Results

DFS: Dynamic Frequency Scaling

Power (Watts)

DFS

Freq

uenc

y (G

Hz)

(s

erve

r spe

ed)

How power affects server speed for a single server

)( minmin PPss

s

P

minP

mins

“linear”P = system power NOT processor power

7

Our Experimental Results

Power (Watts)

DFS

Freq

uenc

y (G

Hz)

How power affects server speed for a single server

Power (Watts)

Freq

uenc

y (G

Hz)

Power (Watts)

Freq

uenc

y (G

Hz)

DVFS DVFS

+DFS

Power (Watts)

DFS

Freq

uenc

y (G

Hz)

Power (Watts)

Freq

uenc

y (G

Hz)

Power (Watts)

Freq

uenc

y (G

Hz)

DVFS DVFS

+DFS

“LINPACK”CPU BOUND

“STREAM”MEM BOUND

8

Power Allocation ResultsCPU bound “LINPACK”

Memory bound

“STREAM”

DFS

DVFS

DVFS+DFS

Power (Watts)

DFS

Freq

uenc

y (G

Hz)

optimal. is PowMax then ,Ps

α steep

and linear is scaling speed If :THEOREM

min

min

minP

mins

9

Power Allocation ResultsCPU bound “LINPACK”

Memory bound

“STREAM”

DFS

DVFS

DVFS+DFS for optimal is PowMin

then ,

P

P

for optimal is PowMax

Ps

αflat and

linear is scaling speed If :THEOREM

min

min

Power (Watts)

Freq

uenc

y (G

Hz)

DVFS

P.

10

Power Allocation ResultsCPU bound “LINPACK”

Memory bound

“STREAM”

DFS

DVFS

DVFS+DFS

0

0

for optimal is PowMed

for optimal is PowMax

then cubic, is scaling speed If :THEOREM

Power (Watts)

Freq

uenc

y (G

Hz)

DVFS+DFS

332

0 minkneeminmaxkneemax

PPPPPP

P

0

11

Power Allocation ResultsCPU bound “LINPACK”

Memory bound

“STREAM”

DFS

DVFS

DVFS+DFS

DVFS+DFS

DFS

DVFS

Arrival rate (jobs/sec)

Mea

n Re

sp. T

ime

(sec

)M

ean

Resp

. Tim

e (s

ec)

Mea

n Re

sp. T

ime

(sec

)

Arrival rate (jobs/sec) Arrival rate (jobs/sec)

12

Conclusions: How to allocate power optimally

Speed Scaling?

Arrival Rate?

Linear, Steep Linear, Flat Cubic

Arrival Rate? Arrival Rate?

PowMax PowMax PowMax PowMin

HighLow HighLow HighLow

PowMax PowMed