2. performance per watt
In computing, performance per watt is a measure of
the energy efficiency of a particular computer
architecture or computer hardware. Literally, it
measures the rate of computation that can be
delivered by a computer for every watt of power
consumed.
System designers building parallel computers, such as
Google's hardware, pick CPUs based on their
performance per watt of power, because the cost of
powering the CPU outweighs the cost of the CPU itself.
3. FLOPS (Floating Point Operations
Per Second) per watt
FLOPS (Floating Point Operations Per Second) per
watt is a common measure. Like the FLOPS it is based
on, the metric is usually applied to scientific computing
and simulations involving many floating point
calculations.
4. Instructions per second (IPS) is a
measure of a computer's
processor speed.
The term is commonly used in association with a numeric value such as
thousand instructions per second (kIPS), million instructions per second
(MIPS), Giga instructions per second (GIPS), or million operations per second
(MOPS).
5. average CPU power (ACP),
The average CPU power (ACP), is a
scheme to characterize power
consumption of new central processing
units under "average" daily usage,
especially server processors, the rating
scheme is defined by Advanced Micro
Devices (AMD) for use in its line of
processors based on the K10
microarchitecture (Opteron 8300 and
2300 series processors)
6. thermal design power (TDP),
The thermal design power (TDP),
sometimes called thermal design point, is
the maximum amount of heat generated
by the CPU that the cooling system in a
computer is required to dissipate in typical
operation. Rather than specifying CPU's
real power dissipation, TDP serves as the
nominal value for designing CPU cooling
systems.
7. CPU power dissipation
Central processing unit power dissipation
or CPU power dissipation is the process in
which central processing units (CPUs)
consume electrical energy, and dissipate
this energy both by the action of the
switching devices contained in the CPU
(such as transistors or vacuum tubes) and
by the energy lost in the form of heat due
to the impedance of the electronic circuits.
8. CPU power dissipation
There are several factors contributing to the CPU power consumption; they
include dynamic power consumption, short-circuit power consumption, and
power loss due to transistor leakage currents:
Pcpu = Pdyn + Psc + Pleak
The dynamic power consumption originates from logic-gate activities in the
CPU. When logic gates toggle, energy is flowing as capacities inside the
logic gates are charged and discharged. The dynamic power consumed by
a CPU is approximately proportional to the CPU frequency, and to the
square of the CPU voltage:
P = CV2f
where C is capacitance, f is frequency, and V is voltage.
14. "Moore's law" is the
observation that, over the
history of computing hardware,
the number of transistors in a
dense integrated circuit
doubles approximately every
two years.
21. The first part (addend) of the equation accounts for
the dynamic power consumption on the chip (i.e. the
power consumption caused by charging and
discharging capacitive loads when transistors are
switched) that represents the useful work performed
by the chip. A is the activity factor meaning the
proportion of switching transistors in each cycle (since
not all transistors have to switch every clock cycle); C is
the capacitive load of the transistor; V is the voltage;
and f is the frequency.
22. The first part (addend) of the equation accounts for
the dynamic power consumption on the chip (i.e. the
power consumption caused by charging and
discharging capacitive loads when transistors are
switched) that represents the useful work performed
by the chip. A is the activity factor meaning the
proportion of switching transistors in each cycle (since
not all transistors have to switch every clock cycle); C is
the capacitive load of the transistor; V is the voltage;
and f is the frequency.
23. If we observe the first term of the equation we can see
why power has being increasing only linearly while
frequency has been doing it logarithmically. The
reason is the quadratic dependence on the voltage.
24. Engineers have been able to continuously reduce this voltage
from 5V down to below 1V, which has helped them to control
dissipated power without losing performance. Unfortunately,
many factors are interdependent and engineers have to make
trade-offs constantly. For example, imagine we want to
decrease dynamic power consumption on a chip (consider only
first term of the equation) by reducing the supply voltage
initially fixed at 2V. If we are able to reduce it to 1.7V, it is only a
15% decrease in voltage but we get a significant 28% decrease
in power. However, reducing supply voltage has a side-effect
on the maximum frequency for the circuit and on the threshold
voltage of transistors (the voltage at which a transistor switches
on):
45. Clock-gating inserts a clock-
enable before each state
element (register, latch, etc.)
such that the element is not
clocked if new data is not going
to be written.
52. Intel Core 2 Duo 2.0 GHz processor
2 GB RAM
32 GB solid state hard drive
13.3" 1280x800 LED backlit display
NVIDIA GeForce Go 8400M GS video
Windows Vista Ultimate
61. 1.Don't do anything with 3D graphics (gaming, etc)
2.Avoid using DVDs
3.Turn down the screen brightness 1 or 2 notches
4.Avoid CPU intensive web pages or programs
62. Intel Core 2 Duo 2.0 GHz processor
2 GB RAM
32 GB solid state hard drive
13.3" 1280x800 LED backlit display
NVIDIA GeForce Go 8400M GS video
Windows Vista Ultimate