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GreenDroid is a 45 nm multicore research prototype that targets the Android mobile phone software stack and can execute general-purpose mobile programs with 11 times less energy than today’s most energy-efficient designs, at similar or better levels of performance. It does this through the use of 100 or so automatically generated, highly specialized, energy-reducing cores, called conservation cores or c-cores. GreenDroid will serve as a prototype for mobile application processors in the next five to ten years.
So greendroid is always better than android.
MVGR College Of Engg.
THE FUTURE OF ANDROID
ANDROID THE BEGINNING
It is an open source software platform and operating system for
It is based on Linux kernel.
Developed by Google and later the Open Handset Alliance .
Allows writing the managed code in Java language
Android has its own virtual machine DVM(DALVIK VIRTUAL
MACHINE),which is used for executing the android application.
It has evolved from the first version named as Android 1.0 to the
latest version Android 6.0(released in October 2015).
The software stack is split into five ways:
1. The application layer(The browser and the contacts
work with the help of the application layer)
2. The application framework(This is the toolkit that all
applications use, like the inbuilt programs and also the
3. The libraries(Android has its own libraries, written in
C/C++,for web browsing a web library and for video
playing a video library, etc)
4. Run Time
5. The Linux Kernel (provides services like power
management and service management)
DISADVANTAGES OF ANDROID
Android Market is less control of the manager sometimes there is
Wasteful Batteries, This is because there is a lot of process in the
background causing the battery quickly drains.
Sometimes the device is slow even though it is an official version
of the android .
Extremely inconsistent in design among apps.
Very unstable and often hang or crash.
Greendroid is intended to help people in designing Android
Keep in mind, it is still a work in progress!
The Greendroid mobile application processor is a 45-nm multi
core research prototype that targets the Android mobile-phone
software stack and can execute general-purpose mobile
programs with 11 times less energy than today’s most energy-
efficient designs, at similar or better performance levels. It does
this through the use of a hundred or so automatically generated,
highly specialized, energy-reducing cores, called conservation
The research attacks a key technological problem for
microprocessor architects, which is called the utilization wall.
THE UTILIZATION WALL
The utilization wall says that, with
each process generation, the
percentage of transistors that a chip
design can switch at full frequency,
drops exponentially because of
It is expected that as the size of the
chip decreases the utilization of the
chip also decreases as you can see on
the chip .For a every reduction in
size there is a reduction in
THE DARK SILICON
Power and Area go hand by hand when we are designing a
circuit .We need to be precise with our power and so with our
But what happens is in our mobile processors large swath’s of
chips silicon area must remain passive in order to meet the power
limitations in the chip.
With each generation power limitations are becoming
exponentially very high.
Only 1 % of 32nm sized chip can operate completely at full
frequency at a power budget of 3W
Conventional chip designs in a mobile phone lose significant energy
due to the presence of unused transistors called dark silicon. Dark
silicon is when we have three billion transistors on our chip but we
can only use 1.8 percent of them at a time, so as to squeak under the
threshold of our chip's draconian energy budget.
The dark silicon problem is directly responsible for the desktop
processor industry’s decision to stop scaling clock frequencies and
instead build multi-core processors.
Dark silicon is necessary, because engineers are unable to reduce
chips' operating voltages any further to offset increases in power
consumption and waste heat produced by smaller, faster chips . This
dark silicon limits the utilization of the application processors to the
WHAT DO WE DO WITH
Leverage dark silicon to scale the utilization wall
Power is now more expensive than area
Specialized logic can improve energy efficiency
Fill dark silicon with specialized cores to save energy on
Provide focused re configurability to handle evolving
It follows the ideology “If you fill the chip with highly
specialized cores, then the fraction of the chip that is lit up
at one time can be the most energy efficient for that
particular task”. These highly specialized cores are known
as conservation cores or c-cores.
To pursue this goal Conservation cores, or c-cores, are
specialized processors that focus on reducing energy and
energy-delay instead of increasing performance. This focus
on energy makes c-cores an excellent match for many
applications that would be poor candidates for hardware
acceleration (e.g., irregular integer codes).
ADVANTAGES OF C-CORES
If more amount of area is
accomodated for c cores
then the execution
performance of c cores can
be made more and energy
consumption per instruction
can be reduced.
7 mm2 of c-cores provides:
– 95% execution coverage
– 8x energy savings over
PURPOSE OF GREENDROID
Help developers to code highly functional applications.
The Android framework may look like “over-engineered”
sometimes. Actually, I believe this is a direct consequence of the
fact you can do almost everything you want.
Unfortunately, this openness (again!) makes it harder to
Let’s say for instance, you are a beginner and wants to develop
your own application. You’ll have to read a lot of documentation
in order to be “up and ready”.
GreenDroid makes development a lot easier without
decreasing the powerfulness of the amazing Android framework!
Leverage the power of the Android framework. Developing on
the Android platform may be pretty easy if you’re not taking care
of the resources you’re using. Trying to optimize your application
is quite hard sometimes and is a very demanding task.
GreenDroid has been developed to be as efficient as possible by
integrating basic optimizations.
Use as much XML(EXTENSIBLE MARKUP LANGUAGE) as
possible. It’s not a mystery to anybody. Android UI development is
based on amazing techniques. Layouts and views are defined in
XML and automatically inflated by the system. Being an “easy-to-
read-for-humans” format, XML is very used among Android
developers. GreenDroid puts XML in the middle of the library and
takes advantage of all amazing possibilities offered by Android
A Green Droid processor combines general-purpose processors with
application-specific coprocessors that are very energy efficient.
These conservation cores, or c-cores, execute most of an
application’s code and will account for well over 90 percent of
Green-Droid is a heterogeneous tiled architecture. illustrates how it
uses a grid-based organization to connect multiple tiles.
It contains an energy-efficient 32-bit 7-stage in order pipeline that
runs at 1.5 GHz in a 45 nm process technology
It includes a single-precision floating point unit (FPU),
multiplier, 16- kbyte I-cache, translation look aside buffer
(TLB), and 32-kbyte banked L1 data cache.
The architecture also includes a mesh-based on-chip network
(OCN). The OCN carries memory traffic and supports fast
GreenDroid is a 45 nm multicore research prototype that
targets the Android mobile phone software stack and can
execute general-purpose mobile programs with 11 times less
energy than today’s most energy-efficient designs, at similar
or better levels of performance. It does this through the use of
100 or so automatically generated, highly specialized, energy-
reducing cores, called conservation cores or c-cores.
GreenDroid will serve as a prototype for mobile application
processors in the next five to ten years.
So greendroid is always better than android.
• IEEE Micro 2011(March/April)-Saturnino
Garcia ,Jack Sampson
• Conservation Cores by Jack Sampson
• Integrated Circuits for Communication