ARM big.LITTLEâ„¢ Technology Gaming Audio Playback . 4 Mobile Application Workloads Sustained Performance

1

ARM® big.LITTLE™ Technology Unleashed An Improved User Experience Delivered

Govind Wathan Product Specialist

Cortex®-A Mobile & Consumer CPU Products

2

 Introduction to big.LITTLE Technology

 Benefits of big.LITTLE Technology

 Future big.LITTLE systems

 Summary

 Questions

Agenda

3

 Mobile users spend a high amount of time on a

range of mobile applications*:

 38% on web browsing and Facebook

 32% on gaming

 16% on audio, video and utility

 Common “building blocks” in workloads:

 Short bursts of high intensity

 Long periods of sustained high intensity

 Low intensity

Mobile Application Workloads

Measured on a Quad Cortex-A7 Symmetric Multiprocessing platform

* Source: Flurry Analytics Time

Time

Time

P o w

e r

P o w

e r

P o w

e r

Web Browsing

Gaming

Audio Playback

4

Mobile Application Workloads

Sustained Performance Envelope

Category 2

Sustained Performance

at Thermal Limit

Category 3

Long-use Low-Intensity

Workloads

Category 1

Burst of High Intensity

Workloads

Example: Web Browsing

Example: Castlemaster

Example: Audio Playback

Power

 Applications require a mix of performance levels

 Mobile users want a better user experience but not at a cost of reduced battery life

5

Mobile Application Workload Profiles P e rc

e n ta

ge o

f T im

e S

p e n t

in

D V

F S

St at

e s

Category 2

Sustained Performance

at Thermal Limit

Category 3

Long-use Low-Intensity

Workloads

Category 1

Burst High Intensity Workloads

High

Mid

Low

WFI / Power Down

Measured on a Quad Cortex-A7 Symmetric Multiprocessing platform

 Applications require a mix of performance levels

 Mobile users want a better user experience but not at a cost of reduced battery life

Idle

Example: Web Browsing

Example: Castlemaster

Example: Audio Playback

6

 Heterogeneous Computing

 2x higher performance vs. LITTLE only

 Up to 75% CPU power savings vs. big only

 Architecturally Identical Processors

 High performance tuned big cores

 Low power tuned LITTLE cores

 Hardware Coherency

 Cache Coherent Interconnect (CCI)

 L1 and L2 snooping between clusters

 Seamless & Automatic Task Allocation

big.LITTLE Technology

“Right Task on the Right Core”

L2 Cache L2 Cache

Cache Coherent Interconnect

Interrupt Control

Up to 40% SOC power savings*

* Measured across a set of casual games and common use-cases on an ARM

Partner 4xCortex-A15.4xCortex-A7 big.LITTLE device

big Cluster

LITTLE Cluster

7

 Introduction to big.LITTLE Technology

 Benefits of big.LITTLE Technology

 Future big.LITTLE systems

 Summary

 Questions

Agenda

8

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

Cluster Migration

big.LITTLE MP

Power

big.LITTLE MP Software Evolution

big.LITTLE

Cluster

Migration

CPU

Migration

Global Task

Scheduling

(big.LITTLE MP)

1

2

2

2

2

1

1

1

1 1

2

3

4

2

3

4

1

2

3

4

Improving Performance and Efficiency

2012 H1 2013 H2 2013

Measured Power and Performance on big.LITTLE Devices

(big.LITTLE MP relative to Cluster Migration)

-29% -38% +20%

+60% 5

6

7

8

Performance

Web

Browsing

Intensive

Gaming

Web Browsing

Intensive

Gaming

(Lower is Better) (Higher is Better)

9

big.LITTLE MP

 Delivers higher power efficiency

 Extends battery life

 Improves user experience

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

Cluster Migration

big.LITTLE MP

Power

Measured Power and Performance on big.LITTLE Devices

(big.LITTLE MP relative to Cluster Migration)

-29% -38% +20%

+60%

Performance

Web

Browsing

Intensive

Gaming

Web Browsing

Intensive

Gaming

(Lower is Better) (Higher is Better)

10

Asphalt 7 Dungeon Defenders

Video Playback

Normalized Jank* (Less is Better)

LITTLE only

big.LITTLE

big.LITTLE MP Improves User Experience (UX)

* Measure of variance in frame rate

Measurements conducted on the same big.LITTLE platform

58% 65% 47% UX

Improvement

0%

20%

40%

60%

80%

100%

CPU0 CPU1 CPU2 CPU3 CPU4 CPU5

DVFS states: Web Browsing with Audio

LITTLE core Idle LITTLE core Low Frequency

LITTLE core Mid Frequency LITTLE core High Frequency

big core Idle big core Low Frequency

big core Mid Frequency big core High Frequency

Short bursts of performance on big cores enable

sustained levels of smooth user-experience

LITTLE cores handle background tasks and audio

LITTLE Cluster big Cluster

†

†

†

11

0.00

0.50

1.00

1.50

2.00

4x4 big.LITTLE MP vs. 4x4 Cluster Migration

Efficiency

 SoC thermal budget constrains Cortex-A15

cores to lower frequency resulting in lower

benchmark performance

 35% average improvement in power efficiency across

Single-Thread and Multi-Thread workloads

1.2GHz

Cortex-A15 MP4 Cortex-A7 MP4

1.3 GHz

Frequency residency profile while running Antutu CPU

big.LITTLE MP

Cluster

Migration

big.LITTLE MP Delivers Higher Power Efficiency

 Cortex-A15 and Cortex-A7 clusters at peak

performance within the thermal budget

1.7GHz 1.1GHz

1.4GHz

1.2GHz

Cortex-A15 MP4

A7 cores not running

due to cluster migration

Cortex-A7 MP4

Cluster

Migration

Power Efficiency

12

big.LITTLE MP Extends Battery Life

0%

50%

100%

150%

200% Cluster Migration

big.LITTLE MP

0%

20%

40%

60%

80%

100%

A7 CPU0 A7 CPU1 A7 CPU2 A7 CPU3 A15 CPU4 A15 CPU5

DVFS states : Temple run

LITTLE core idle LITTLE core low frequency

LITTLE core Med frequency LITTLE core high frequency

big core idle big core low frequency

big core Med frequency big core high frequency

LITTLE Cluster big Cluster

Cores in the big cluster are powered down

Single-thread performance on highly efficient

LITTLE cores enable increased power savings

Relative battery life on big.LITTLE MP

13

 big.LITTLE MP Software

 http://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git

 Linaro Landing Teams for Club and Core Members

 Provides Software Support under NDA

 Exclusive Landing Teams for each Member company

 Services and Support Offered through ARM

 Active Assist Design Review – big.LITTLE system

 Technical Support & Application Notes

 big.LITTLE MP Integration and Tuning Guides

 On-site Software Training

big.LITTLE MP Support and Services Available

http://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git http://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git http://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git

14

Agenda

 Introduction to big.LITTLE Technology

 Benefits of big.LITTLE Technology

 Future big.LITTLE systems

 Summary

 Questions

15

 Improved performance on big.LITTLE ARMv8

 Cortex-A57: Highest performance big CPU in thermal envelope

 Cortex-A53: Most energy efficient LITTLE CPU

ARMv8-A Enables 64-bit big.LITTLE