Transcript Yonsei University

Chapter 2
Computer Evolution and
Performance
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Contents
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2-2
A Brief History of Computers
Designing for Performance
Pentium and PowerPC Evolution
Performance Evaluation
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ENIAC
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A brief history
of computers
Electronic Numerical Integrator And Computer
John Mauchly and John Presper Eckert
Trajectory tables for weapons
Started 1943 / Finished 1946
– Too late for war effort
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Used until 1955
Decimal (not binary)
20 accumulators of 10 digits
Programmed manually by switches
18,000 vacuum tubes
30 tons
1,500 square feet
140 kW power consumption
5,000 additions per second
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von Neumann/Turing
A brief history
of computers
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•
•
•
Stored Program concept
Main memory storing programs and data
ALU operating on binary data
Control unit interpreting instructions from
memory and executing
• Input and output equipment operated by
control unit
• Princeton Institute for Advanced Studies
– IAS
• Completed 1952
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von Nuemann Machine
Input
Output
Equipment
Arithmetic
And
Logic Unit
A brief history
of computers
Main
Memory
Program
Control Unit
• If a program could be represented in a form
suitable for storing in memory, the programming
process could be facilitated
• A computer could get its its instructions from
memory, and a program could could be set or
altered by setting the values of a portion of
memory
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IAS Memory Formats
A brief history
of computers
01
39
(a) Number Word
Sign Bit
Left Instruction
0
Right Instruction
8
Opcode
19 20
Address
28
Opcode
39
Address
(b) Instruction Word
• 1000 x 40 bit words
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–
–
–
2-6
Binary number
2 x 20 bit instructions
Each instruction consisting of an 8-bit opcode
A 12-bit address designating one of the words in
memory
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IAS Registers
A brief history
of computers
• Memory Buffer Register
– Containing a word to be stored in memory, or used
to
receive a word from memory
• Memory Address Register
– Specifying the address in memory of the word to
be written from or read into the MBR
• Instruction Register
– Containing the 8-bit opcode instruction being
executed
• Instruction Buffer Register
– Employed to hold temporarily the righthand
instruction from a word memory
• Program Counter
– Containing the address of the next instruction-pair
to be fetched from memory
• Accumulator and Multiplier Quotient
– Employed to hold temporarily operands and
results of ALU operations.
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Structure of IAS
A brief history
of computers
Central Processing Unit
Arithmetic and Logic Unit
Accumulator
MQ
Arithmetic & Logic Circuits
MBR
Input
Output
Equipment
Instructions
Main
& Data
Memory
PC
IBR
MAR
IR
Control
Circuits
Program Control Unit
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Address
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Partial Flowchart of IAS
A brief history
of computers
Start
Yes
No Memory
Access
required
Fetch
Cycle
IR ← IBR (0:7)
MAR ← IBR (8:19)
Is Next
Instruction
In IBR?
No
MAR ← PC
MBR ← M(MAR)
IR ← IBR (20:27)
MAR←IBR(28:39)
No
Left
Instruction
Required?
Yes
IBR←MBR(20:39)
IR ← MBR (0:7)
MAR ←MBR(8:19)
PC ← PC+1
AC ← M(X)
Go to M(X, 0:19)
ExecuMBR ← M(MAR)
tion
Cycle
AC ← MBR
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Decode instruction in IR
If AC ≥ 0 then
Go to M(X, 0:19)
Yes
PC ← MAR
Is AC ≥ 0?
No
AC ← AC + M(X)
MBR ← M(MAR)
AC ← MBR
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The IAS Instruction Set
2-10
A brief history
of computers
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The IAS Instruction Set
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A brief history
of computers
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The IAS Instruction Set
A brief history
of computers
• Data transfer
– Move data between memory and ALU registers or
between two ALU registers
• Unconditional branch
– This sequence can be changed by a branch
instruction allowing decision points
• Conditional branch
– The branch can be made dependent on a
condition, thus allowing decision points
• Arithmetic
– Operations performed by the ALU
• Address modify
– Permits addresses to be computed in the ALU and
then inserted into instruction stored in memory.
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Commercial Computers
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A brief history
of computers
1947 - Eckert-Mauchly Computer Corporation
UNIVAC I (Universal Automatic Computer)
US Bureau of Census 1950 calculations
Became part of Sperry-Rand Corporation
Late 1950s - UNIVAC II
– Faster
– More memory
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IBM
A brief history
of computers
• Had helped build the Mark I
• Punched-card processing equipment
• 1953 - the 701
– IBM’s first stored program computer
– Scientific calculations
• 1955 - the 702
– Business applications
• Lead to 700/7000 series
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Computer Generations
2-15
Generation
Approximate
Dates
1
2
3
1946-1957
1958-1964
1965-1971
4
1972-1977
5
1978-
.
A brief history
of computers
Technology
Vacuum tube
Transistor
Small- and
Medium-scale
Integration
Large-scale
Integration
Very-large-scale
Integration
Typical Speed
(operations per
second)
40,000
200,000
1,000,000
10,000,000
100,000,000
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Transistors
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2-16
A brief history
of computers
Replaced vacuum tubes
Smaller
Cheaper
Less heat dissipation
Solid State device
Made from Silicon (Sand)
Invented 1947 at Bell Labs
William Shockley et al.
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Transistor Based Computers
A brief history
of computers
• Second generation machines
• NCR & RCA produced small transistor
machines
• IBM 7000
• Digital Equipment Corporation (DEC) - 1957
– Produced PDP-1
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IBM 700/7000 Series
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Model
Number
First
Delivery
701
1952
Vacuum
Tubes
704
1955
709
A brief history
of computers
CPU
Memory
Technology Technology
Cycle
Time(㎲)
Memory
Size(K)
ElectroStatic tubes
30
2-4
Vacuum
Tubes
Core
12
4-32
1958
Vacuum
Tubes
Core
12
32
7090
1960
Transistor
Core
2.18
32
7094 I
1962
Transistor
Core
2
32
7094 II
1964
Transistor
Core
1.4
32
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IBM 700/7000 Series
A brief history
of computers
Number Hardwired
I/O
Instruction
of Index
Floating
Overlap
Fetch
Registers
Point
(Channels) Overlap
Speed
(relative
To 701)
Model
Number
Number
of Opcodes
701
24
0
No
No
No
1
704
80
3
Yes
No
No
2.5
709
140
3
Yes
Yes
No
4
7090
169
3
Yes
Yes
No
25
Yes
Yes
30
Yes
Yes
50
7094 I
185
7
7094 II
185
7
2-19
Yes
(double
Precision)
Yes
(double
Precision)
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An IBM 7094 Configuration
A brief history
of computers
Mag Tape
Units
CPU
Data
Channel
Card
Punch
Line
Printer
Card
Reader
Multiplexor
Drum
Data
Channel
Disk
Data
Channel
Disk
Hypertapes
Memory
Data
Channel
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Teleprocessing
Equipment
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The IBM 7094
A brief history
of computers
• The most important point is the use of data
channels. A data channel is an independent
I/O module with its own processor and its own
instruction set.
• Another new feature is the multiplexor, which
is the central termination point for data
channel, the CPU, and memory.
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Microelectronics
A brief history
of computers
• Literally - “small electronics”
• A computer is made up of gates, memory
cells and interconnections
• These can be manufactured on a
semiconductor
• e.g. silicon wafer
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Microelectronics
A brief history
of computers
• Data storage
– Provided by memory cells
• Data processing
– Provided by gates
• Data movement
– The paths between components are used to move
data from memory to memory and from memory
through gates to memory
• Control
– The paths between components can carry control
signals. The memory cell will store the bit on its
input lead when the WRITE control signal is ON
and will place that bit on its output lead when the
READ control signal is ON.
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Wafer, Chip, and Gate
A brief history
of computers
Wafer
Chip
Package
Chip
Gate
• Small-scale integration (SSI)
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Generations of Computer
A brief history
of computers
• Vacuum tube - 1946-1957
• Transistor - 1958-1964
• Small scale integration - 1965 on
– Up to 100 devices on a chip
• Medium scale integration - to 1971
– 100-3,000 devices on a chip
• Large scale integration - 1971-1977
– 3,000 - 100,000 devices on a chip
• Very large scale integration - 1978 to date
– 100,000 - 100,000,000 devices on a chip
• Ultra large scale integration
– Over 100,000,000 devices on a chip
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Moore’s Law
A brief history
of computers
• Increased density of components on chip
• Gordon Moore - cofounder of Intel
• Number of transistors on a chip will double
every year
• Since 1970’s development has slowed a little
– Number of transistors doubles every 18 months
• Cost of a chip has remained almost unchanged
• Higher packing density means shorter electrical
paths, giving higher performance
• Smaller size gives increased flexibility
• Reduced power and cooling requirements
• Fewer interconnections increases reliability
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Growth in CPU Transistor Count
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A brief history
of computers
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IBM 360 series
A brief history
of computers
• 1964
• Replaced (& not compatible with) 7000 series
• First planned “family” of computers
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Similar or identical instruction sets
Similar or identical O/S
Increasing speed
Increasing number of I/O ports(i.e. more terminals)
Increased memory size
Increased cost
• Multiplexed switch structure
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Key Characteristics of 360 Family
A brief history
of computers
• Many of its features have become standard
on other large computers
Characters
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Model 30 Model 40 Model 50 Model 65 Model 75
Maximum memory size (bytes)
64K
256K
256K
512K
512K
Data rate from memory
(Mbytes/s)
0.5
0.8
2.0
8.0
16.0
Processor cycle time (㎲)
1.0
0.625
0.5
0.25
0.2
Relative speed
1
3.5
10
21
50
Maximum number of data
channels
3
3
4
6
6
Maximum data rate on one
channel (Mbytes/s)
250
400
800
1250
1250
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DEC PDP-8
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•
A brief history
of computers
1964
First minicomputer (after miniskirt!)
Did not need air conditioned room
Small enough to sit on a lab bench
$16,000
– $100k+ for IBM 360
• Embedded applications & OEM
• Later models of the PDP-8 used a bus structure
that is now virtually universal for minicomputers
and microcomputers
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PDP-8/E Block Diagram
A brief history
of computers
• Highly flexible architecture allowing modules to be
plugged into the bus to create various configurations
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Semiconductor Memory
A brief history
of computers
• The first application of integrated circuit
technology to computers
– construction of the processor
– also used to construct memories
• 1970
• Fairchild
• Size of a single core
– i.e. 1 bit of magnetic core storage
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Holds 256 bits
Non-destructive read
Much faster than core
Capacity approximately doubles each year
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Evolution of Intel Microprocessors
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A brief history
of computers
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Evolution of Intel Microprocessors
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A brief history
of computers
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Evolution of Intel Microprocessors
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A brief history
of computers
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Microprocessor Speed
Design for
performance
• In memory chips, the relentless pursuit of speed
has quadrupled the capacity of DRAM, every
years
• Pipelining
• On board cache
• On board L1 & L2 cache
• Branch prediction
• Data flow analysis
• Speculative execution
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Design for
Evolution of DRAM / Processor Characteristics performance
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Performance Mismatch
Design for
performance
• Processor speed increased
• Memory capacity increased
• Memory speed lags behind processor speed
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Performance Balance
Design for
performance
• It is responsible for carrying a constant flow of
program instructions and data between memory
chips and the processor → The interface between
processor and main memory is the most crucial
pathway in the entire computer
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Trends in DRAM use
2-40
Design for
performance
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Performance Balance
Design for
performance
• On average, the number of DRAMs per
system is going down.
• The solid black lines in the figure show that,
for a fixed-sized memory, the number of
DRAMs needed is declining
• The shaded bands show that for a particular
type of system, main memory size has slowly
increased while the number of DRAMs has
declined
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Solutions
Design for
performance
• Increase number of bits retrieved at one time
– Make DRAM “wider” rather than “deeper”
• Change DRAM interface
– Cache
• Reduce frequency of memory access
– More complex cache and cache on chip
• Increase interconnection bandwidth
– High speed buses
– Hierarchy of buses
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Performance Balance
Design for
performance
• Two constantly evolving factors to be coped
with
– The rate at which performance is changing in the
various technology areas differs greatly from one
type of element to another
– New applications and new peripheral devices
constantly change the nature of the demand on
the system in terms of typical instruction profile
and the data access patterns.
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Intel
Pentium and PowerPC evolution
• Pentium - results of design effort on CISCs
• 1971 - 4004
– First microprocessor
– All CPU components on a single chip
– 4 bit
• Followed in 1972 by 8008
– 8 bit
– Both designed for specific applications
• 1974 - 8080
– Intel’s first general purpose microprocessor
• 8086
– 16 bit, instruction cache, or queue
• 80286
– addressing a 16-Mbyte memory
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Intel
Pentium and PowerPC evolution
• 80386
– 32 bit, multitasking
• 80486
– built-in math coprocessor
• Pentium
– superscalar techniques
• Pentium Pro
• Pentium II
– Intel MMX thchnology
• Pentium III
– additional floating-point instruction
• Merced
– 64-bit organization
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PowerPC
Pentium and PowerPC evolution
• RISC systems
• PowerPC Processor Summary
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Two Notions of Performance
Performance evaluation
Plane
DC to Paris
Speed
Passengers
Throughput
(pmph)
Boeing 747
6.5 hours
610 mph
470
286,700
BAD/Sud
Concodre
3 hours
1350 mph
132
178,200
• Which has higher performance?
– Time to do the task (Execution Time)
• execution time, response time, latency
– Tasks per day, hour, week, sec, ns. ..
(Performance)
• throughput, bandwidth
– Response time and throughput often are in
opposition
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To Assess Performance
Performance evaluation
• Response Time
– Time to complete a task
• Throughput
– Total amount of work done per time
• Execution Time (CPU Time)
– User CPU time
• Time spent in the program
– System CPU time
• Time spent in OS
• Elapsed Time
– Execution Time + Time of I/O and time sharing
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Criteria of Performance
Performance evaluation
• Execution time seems to measure the power
of the CPU
• Elapsed time measures the performance of
whole system including OS and I/O
• User is interested in elapsed time
• Sales people are interested in the highest
number of performance that can be quoted
• Performance analysist is interested in both
execution time and elapsed time
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Definitions
Performance evaluation
• Performance is in units of things-per-second
– bigger is better
• If we are primarily concerned with response
time
– performance(x) =
1
execution_time(x)
" X is n times faster than Y" means
n
2-50
=
Performance(X)
---------------------Performance(Y)
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Example
Performance evaluation
• Time of Concorde vs. Boeing 747?
– bigger is better
– Concord is 1350 mph / 610 mph = 2.2 times faster
= 6.5hours/3hours
• Throughput of Concorde vs. Boeing 747 ?
– Concord is 178,200 pmph / 286,700 pmph
= 0.62 times faster
– Boeing is 286,700 pmph / 178,200 pmph
= 1.6 times faster
• Boeing is 1.6 times (60% faster in terms of
throughput
• Concord is 2.2 times (220% faster in terms of
flying time
• We will focus primarily on execution time for a
single job
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Basis of Evaluation
Cons
Pros
• representative
Actual Target Workload
• portable
• widely used
• improvements
useful in reality
• easy to run, early in
design cycle
• identify peak
capability and
potential bottlenecks
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Performance evaluation
• very specific
• non-portable
• difficult to run, or
measure
• hard to identify cause
•less representative
Full Application Benchmarks
Small kernel
Benchmarks
Microbenchmarks
• easy to cool
• peak may be a long
way from application
performance
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MIPS
Performance evaluation
• Millions of Instruction(Executed) Per Second
• Often used measure of performance
• Native MIPS
=
=
=
=
2-53
clock rate
CPI × 106
instruction count
execution time × 106
instruction count
CPU clocks × cycle time × 106
instruction count × clock rate
cycle time × 106
instruction count × clock rate
instruction count × CPI × 106
clock rate
CPI × 106
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MIPS
Performance evaluation
• Meaningless information
– Run a program and time it
– Count the number of executed instruction to get
MIPs rating
• Problems
– Cannot compare different computers with different
instruction sets
– Varies between programs executed on the same
computer
• Peak MIPS
– This is what many manufacturers provide
– Usually neglecting ‘peak’o
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Relative MIPS
Performance evaluation
• Call VAX 11/780 1 MIPS machine (not true)
CPU time of VAX 11/780
• .
× MIPS of VAX 11/780
CPU time of machine A
CPU time of VAX 11/780
• .
CPU time of machine A
• Makes MIPS rating more independent of
benchmark programs
• Advantage of relative MIPS is small
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FLOPS
Performance evaluation
• Million Floating Point Instructions Per Second
• Used for engineering and scientific
applications where floating point operations
account for a high fraction of all executed
instructions
• Problems
– Program dependent
– Many programs does not use floating point
operations
– Machine dependent
– Depends on relative mixture of integer and floating
point operations
– Depends on relative mixture of cheep(+.-) and
expensive(×) floating point operations
• Normalized FLOPS (relative FLOPS)
• Peak FLOPS
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SPEC Marks
Performance evaluation
• System Performance Evaluation Coorperative
• Non-profit group initially founded by APOLLO,
HP, MIPSCO, and SUN
• Now includes many more like IBM, DEC,
AT&T, MOTOROLA, etc
• Measures the ratio of execution time on the
target measure to that on a VAX 11/780
• Summarizes performance by taking the
geometric means of the ratios
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SPEC95
Performance evaluation
• Eighteen application benchmarks (with inputs)
reflecting a technical computing workload
• Eight integer
– go, m88ksim, gcc, compress, li, ijpeg, perl, vortex
• Ten floating-point intensive
– tomcatv, swim, su2cor, hydro2d, mgrid, applu,
turb3d, apsi, fppp, wave5
• Must run with standard compiler flags
– eliminate special undocumented incantations that
may not even generate working code for real
programs
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Metrics of performance
Performance evaluation
Answers per month
Application
Useful Operations per second
Programming
Language
Compiler
ISA
(millions) of Instructions per second ?MIPS
(millions) of (F.P.) operations per second ?MFLOP/s
Datapath
Control
Megabytes per second
Function Units
Transistors Wires Pins
Cycles per second (clock rate)
Each metric has a place and a purpose, and each can be misused
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Aspects of CPU Performance
CPU time
= Seconds
Program
Performance evaluation
= Instructions x Cycles
Program
instr. count
x Seconds
Instruction
CPI
Cycle
clock rate
Program
Compiler
Instr. Set Arch
Organization
Technology
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Criteria of Performance
Performance evaluation
• CPU Time
– (Instruction count) × (CPI) × (Clock Cycle)
cycle
second
×
– number of Instructions ×
instruction
cycle
• Clock Rate
cycle
–.
seconds
– Depends on technology and organization
• CPI
– Cycles Per Instruction
– Depends on organization and instruction set
• Instruction Count
– Depends on compiler and instruction set
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Criteria of Performance
Performance evaluation
• If CPI is not uniform across all instructions
n
– CPU cycles = Σ i=1 (CPIi × Ii)
• n - number of instructions in instruction set
• CPIi - CPI for instruction i
• Ii - number of times instruction i occurs in a
program
• CPU Time = Σ i=1 (CPIi × Ii × clock cycle)
n
Σ i=1(CPIi × Ii)
• CPI =
number of executed instruction
n
• It assumes that a given instruction always
takes the same number of cycles to execute
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Aspects of CPU Performance
CPU time
= Seconds
Program
= Instructions x Cycles
Program
instr. count
2-63
CPI
X
Compiler
X
X
Instr. Set
X
X
Technology
x Seconds
Instruction
Program
Organization
Performance evaluation
X
Cycle
clock rate
X
X
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CPI
Performance evaluation
average cycles per instruction
CPI = (CPU Time * Clock Rate) / Instruction Count
= Clock Cycles / Instruction Count
n
CPU time = ∑ (Clock Cycle Time × CPI i × I I)
i=1
n
CPI = ∑ CPI i × F i
i=1
where F i
Ii
=
Instruction Count
"instruction frequency"
Invest Resources where time is Spent!
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Example of RISC
Base Machine (Reg / Reg)
Op
Freq Cycles CPI(i)
ALU
50%
1
.5
Load
20%
5
1.0
Store
10%
3
.3
Branch
20%
2
.4
2.2
Performance evaluation
% Time
23%
45%
14%
18%
Typical Mix
How much faster would the machine be is a better data cache
reduced the average load time to 2 cycles?
How does this compare with using branch prediction to shave a
cycle off the branch time?
What if two ALU instructions could be executed at once?
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Amdahl's Law
Performance evaluation
Speedup due to enhancement E:
ExTime w/o E
Performance w/ E
Speedup(E) = -------------------- = -------------------------ExTime w/ E
Performance w/o E
Suppose that enhancement E accelerates a
fraction F of the task by a factor S and the
remainder of the task is unaffected then,
ExTime(with E) ((1-F) + F/S) X ExTime(without E)
Speedup(with E) .
1
.
(1-F) + F/S
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Cost
Performance evaluation
• Traditionally ignored by textbooks because of
rapid change
• Driven by learning curve : manufacturing
costs decrease with time
• Understanding learning curve effects on yield
is key to cost projection
• Yield
– Fraction of manufactured items that survive the
testing procedure
• Testing and Packaging
– Big factors in lowering costs
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Cost
Performance evaluation
• Cost of Chips
– Cost =
manufacture + testing + packaging
final yield
– Cost of die =
cost of wafer
dies per wafer × die yield
– Wafer Yield = dies / wafer
• Cost vs. Price
–
–
–
–
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Component cost : 15~33%
Direct cost : 6~8%
Gross margin : 34~39%
Average discount : 25~40%
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