M.S.Ramaiah School of Advanced Studies 1

Performance comparison between x86 and

ARM Assembly

Manasa.K CWB0912002, FT-2012

M. Sc. (Engg.) in Electronic System Design Engineering

Module leader: Varun Arur

M.S.Ramaiah School of Advanced Studies 2

Contents

• Introduction

• Intel x86 (CISC) processor

• ARM (RISC) processor

• x86 and ARM instructions

• Performance equation

• Intel x86 v/s ARM

• Conclusion

M.S.Ramaiah School of Advanced Studies 3

Introduction Intel x86:

• x86 is a generic name given to Intel processors beginning with the 8086

processor released in 1978.

• Since the earliest machines were programmed in assembly language and

memory was slow and expensive, the CISC was implemented in

computers.

• Intel x86 uses CISC (Complex Instruction Set Computer) and are chips

that are easy to program and which make efficient use of memory.

ARM:

• ARM was first known as Acron RISC Machine, but now its known as

Advanced RISC Machine. ARM was developed in late 70s and 80s.

• This RISC Architecture utilizes a small, highly-optimized set of

instructions, rather than a more specialized set of instructions often found

in other types of architectures.

M.S.Ramaiah School of Advanced Studies 4

Intel x86 (CISC) processor

• x86 is a 16, 32bit CISC processor.

• It has limited number of registers.

• Load and store are incorporated in the instructions itself.

• It has complex instructions.

• Efficiency when compared to ARM is less.

• Different machine programs can be executed on CISC machine.

M.S.Ramaiah School of Advanced Studies 5

ARM (RISC) processor

• ARM is a 32 bit RICS processor.

• It has high code density.

• Load and store architecture.

• 16 bit THUMB instructions.

• Uses simple instructions.

• Conditional execution.

• Inline barrel shifter.

M.S.Ramaiah School of Advanced Studies 6

x86 and ARM Instructions

Multiplying two numbers in memory

To find the product of two numbers, stored in the

locations

Data 1 2:3

Data 2 5:2

Then Store back the product of these in the location 2:3.

Intel x86 (CISC):

MULT 2:3, 5:2

ARM (RISC):

LDR A, 2:3

LDR B, 5:2

MUL A, B

STR 2:3, A

M.S.Ramaiah School of Advanced Studies 7

Cont.… Intel x86:

• If any one of the operand needs to be used for another computation, the processors

must re-load the data from memory into the register.

• The length of the code is relatively short.

• Very little RAM is required to store instructions.

• It requires more transistors, more hardware space, therefore power consumption is

more.

ARM:

• Operand will remain in the register until another value is loaded in its place.

• More number of code lines.

• RAM used is more.

• It requires less transistors so less hardware space therefore power consumption is

less.

M.S.Ramaiah School of Advanced Studies 8

Performance equation

The following equation is commonly used for expressing a

computer's performance ability:

Intel x86 (CISC):

Minimize the number of instructions per program, but takes multiple

clock cycles to execute the entire program.

ARM (RISC):

Minimize the clock cycle per instruction. But has more number of

instructions per program.

M.S.Ramaiah School of Advanced Studies 9

Intel x86:

• More emphasis on speed and performance than power consumption.

• Is compatible with most of the operating systems like Windows 7,

Windows XP, LINUX, Android, Windows Vista, etc.. And these

consumes loads of power.

• Intel x86 is used in laptops, desktops and servers.

ARM:

• Focuses mainly on low power consumption.

• It supports LINUX and Android.

• It is used in all smart phones, iPads tablets etc.

Intel x86 v/s ARM

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Conclusion

ARM offers a distinct advantage over Intel x86, in power

consumption and efficiency. ARM is used in most of the applications

which are portable. Depending on the applications, x86 and ARM

processors are used.

ARM gives tough competition with x86 processors.

Now new windows 8 which is out, supports ARM. If laptops are

replaced by ARM processors, it consumes low power and will have

better battery life.

M.S.Ramaiah School of Advanced Studies 11

References [1] Emily Blem and Jaikrishnan Menon A Detailed Analysis of Contemporary ARM and

x86 Architectures University of Wisconsin - Madison

[2] Mjfern (December 21, 2012) The End of x86? An Update (Online) available from<

http://fernstrategy.com/2012/12/21/the-end-of-x86-an-update/ >[22nd February 2013]

[3] TECH POWER UP (1st December 2011) The Move Away From x86 To ARM

Processors On The Desktop To Start Soon – Survey (Online) available from<

http://www.techpowerup.com/156056/The-Move-Away-From-x86-To-ARM-

Processors-On-The-Desktop-To-Start-Soon-Survey.html> [22nd February 2013]

[4] Rachel Courtland (May 2012) The Battle Between ARM and Intel Gets Real

(Online) available from< http://spectrum.ieee.org/semiconductors/processors/the-battle-

between-arm-and-intel-gets-real> [23rd February 2013]

[5] Van’s Hardware Journal (n.d) Mirror The Coming War ARM versus x86 (Online)

available from< http://vanshardware.com/2010/08/mirror-the-coming-war-arm-versus-

x86/ > [23rd February 2013]

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Thank You