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PPA analysis overview Document ID: 102738_0100_01_en
Version 1.0
Power, performance, and area analysis
2. Power, performance, and area analysis
Power, Performance, and Area (PPA) analysis is performed on an implementation of a piece of IP.
At the point that the analysis is performed, the IP does not exist as a physical product. The purpose
of the analysis is to gain a solid idea of how the implementation would be if it was realized. The
importance of PPA analysis lies in this fact. PPA analysis gives interested parties the chance to
evaluate implementations of a piece of IP before time and money is invested in producing the IP.
Before looking at any specific IP, let’s look at what power, performance, and area mean in the
context of a PPA analysis.
Power
With regard to power, the values of interest are measured in watts. The bottom line is that a piece
of IP could be very energy efficient, but the IP may still use too much power to be a viable choice
for your project. There are two power readings of interest:
•
Dynamic power
•
Static power
Dynamic power
Dynamic power refers to the power that is consumed when the IP clock is running. In the PPA data
provided for the Arm Flexible Access program, dynamic power is always expressed as mW/GHz to
aid comparisons. With processors, you can assume that:
•
A benchmark, for example Dhrystone, was running when the measurements were taken.
•
The processor was running at the maximum cycles possible for its clock setting.
Static power
Static power or leakage is the power that the IP uses when the clock is stopped but the IP is still
powered. In the Arm Flexible Access program PPA data, static power is always expressed in mW to
aid comparisons.
Performance
Performance refers to the maximum clock frequency that the IP can obtain, in a specific
implementation. Performance is measured in MHz or, for more powerful processors, GHz. The
value is also known as the target frequency in an implementation. Achieving higher levels of
performance increases the area and power usage of a processor. This concept is explored further in
Exploring how higher performance can increase the area of the implemented IP.
In this overview, we use the term frequency to describe the performance relating to
the clock frequency of a piece of IP. The term performance is used to describe other
things, for example the data throughput in a cache.
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