Vorlesung 12

Question 1

Intel’s single core assessment

Answer 1

power and area increase more rapidly than performance

Question 2

Why multi-core processors?

Answer 2

POWER – Formeln auf Folie 60

Question 3

What is the evolution of processor performance

Answer 3

Currently, end of the line?, because only 3% processor performance increase can be achieved within a year.

Question 4

ARM LITTLE

Answer 4

most energy efficient application processor from ARM

• simple architecture
• in-order
• 8 stage pipeline

Question 5

ARM big

Answer 5

highest performance in mobile power envelope

• complex architecture
• out-of-order
• multi-issue pipeline

Question 6

When does one use ARM’s little?

Answer 6

“Always on, always connected” tasks like OS, UI activity

Maximum efficiency

Question 7

When does one use ARM’s big

Answer 7

for best performance…

“demanding tasks” like browsers, gaming, content creation

Question 8

What is SGEMM/W?

Answer 8

single-precision general matrix multiplication per Watt

Question 9

What is the lesson learned from nature?

Answer 9

High power efficiency of human brain comes from specialization. More advanced societies have higher degree of specilization.

—–> dedicated architectures have a higher energy efficiency compared to general purpose chip types

Question 10

what is the main task of the zFAS (zentrales Fahrassistenzsteuergerät)

Answer 10

Sensor fusion (signals from stereo cameras, radar, multi-axis acceleration sensors)

Question 11

what does a Field Programmable Gate Array (FPGA) consist of?

Answer 11

A set of programmable macro cells

A programmable interconnection network

Programmable input/outputs

Question 12

what are LUTs and what are they used for?

Answer 12

Look-up tables, used as function generators in memory FPGA

Question 13

characteristics of software

Answer 13

Large flexibility, easy to modify

„Easy“ to learn, many teaching courses

Minimal infrastructure necessary

Large amount of free and open source software

Question 14

characteristics of hardware

Answer 14

Any software requires underlying hardware

Some functions can‘t be implemented in software, e.g., amplifier

Hardware is inherently parallel

Hardware engineering is based on physical laws

Question 15

where does the problem of concurrency in software come from and how can it be solved?

Answer 15

programming languages are usually based on sequential models…

can be solved by having parallelized code

Question 16

What are characteristics of the High-Performance-Computing (HPC) world?

Answer 16

almost unlimited resources

reduce computing time for large computation

but energy is now a big issue!

Question 17

Characteristics of the embedded world

Answer 17

restricted resources (memory, power,…)

heterogeneous architecture

real time and safety critical applications

Question 18

What are the limitations of concurrency in software

Answer 18

Not possible for every algorithm: no independent instructions

More resources do not necessarily reduce the computation time

Splitting the work in two does not mean dividing the time by 2

Using n processors for n tasks might waste resources without decreasing the
computation time

Speed
up depends on the algorithm and is never linear!
Rule of thumb: N processors
√𝑁performance increase

Question 19

What is the rule of thumb for the performance increase based on the number of processors?

Answer 19

N processors lead to a performance increase of √𝑁

Question 20

Amdahl’s Law formula and meaning

Answer 20

PPT

Amdahl’s Law describes performance gain by parallelization

Question 21

Difference between Amdahl’s and Gustafson’s Laws

Answer 21

Amdahl considered a fixed size problem, Gustafson a problem size that scales

Question 22

What are basic types of parallelization and give a quick example

Answer 22

Task parallelism: several independent tasks

data parallelism: split a work into small identical tasks

loop unrolling/pipelining

Question 23

What is the main challenge in parallelization?

Answer 23

Ensure determinism by adding lock mechanisms.

Question 24

What is the problem of parallelization techniques regarding the embedded world

Answer 24

many parallelization techniques not suitable for the embedded world:

Not suitable for safety critical applications

Real time requirements not taken into account

Question 25

What are the three domains of hardware design methodology

Answer 25

behavioral, structural, geometry

Question 26

What is a synthesis

Answer 26

mapping behaviour onto a structure

Question 27

Analysis

Answer 27

extracting behaviour from structure

Question 28

Generation

Answer 28

mapping structure onto geometry

Question 29

Extraction

Answer 29

extracting structure from geometry

Question 30

Synthesis techniques

Answer 30

Circuit synthesis: mapping transfer functions onto transistor structures

Logic synthesis: mapping Boolean equations onto gates

High Level synthesis: mapping RTL specifications onto automatons and datapaths

System synthesis: mapping a system specification onto a mixed HW/SW structure

Question 31

DSP (digital signal processing) Algorithms, steps of the transformation

Answer 31

Allocation:
selecting the number and types of resources
E.g. number of processors, memories, communication

Scheduling:
determines execution order of operations/processes

Mapping:
assigning operations/processes to resources

Question 32

HW/SW codesign flow

Answer 32

PPT

Question 33

HW/SW codesign

Answer 33

PPT

Question 34

ab 105 nicht drin, aber sieht hart useless aus

Answer 34

USELESS