introduction lin zhong elec518, spring 2011. please connect to power
TRANSCRIPT
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Introduction
Lin ZhongELEC518, Spring 2011
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Please connect to power
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Battery density
10% vs. 50% Annual Growth Rate
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One watt steady power13°C surface temperature increase
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Burning pain: 41-43°CTissue damage: 45°C
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Electricity bill
• Data center– Electricity bill is more than equipment bill
• Home appliances
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There is no silver bullet for an energy-efficient mobile device
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DEEP SLE
EP
SLEEP
Compu
ting
LCD
Ligh
ting-
1
Ligh
ting-
2
Ligh
ting-
3
Ligh
ting-
4
Keybo
ard
light
ing
Speak
er
Speak
er-M
ax
WiF
i-Con
necte
d (B
atte
ry)
WiF
i-Con
necte
d (P
erf.)
WiF
i dat
a tra
nsfe
r (1M
bps)
Bluet
ooth
(Disc
over
able
)
Bluet
ooth
(Pag
ing)
Bluet
ooth
(Con
necte
d)
Bluet
ooth
dat
a tra
nsfe
r (11
5kbp
s)
GSM (s
tay c
onne
cted)
GSM vo
ice
GPRS0
200
400
600
800
1000
1200
1400
1600
1800
5 3
221142
88 92 80 93142
2
180
315
704
1615
990
3297
25
900
725
Pow
er
(mW
)
Power profile: T-Mobile MDA
Power profile !=Energy profile
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Rule No. 1• Focus on the big one!
– Amdahl’s Law• Reduction of the power of α % of the system by p% leads to
α∙p % reduction of the total power
10
α
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Rule No. 2
• Minimize static energy consumption– IC consumes static power when it is merely
powered
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Rule No. 3
• Minimize activity– When not doing things useful
• Turn it off• Stop the clock• Check the manual for power-saving modes• Be aware of state transition overhead
– Interrupt-driven instead of polling
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Rule No. 4
• Don’t forget parasites – More integrated solution leads to lower energy
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