Lecture 04 chapter 2 - Parallel Programming Platforms

Parallel and Distributed Computing
Chapter 2: Parallel Programming Platforms
1
Muhammad Haroon
mr.harunahmad2014@gmail.com
Cell# +92300-7327761
Department of Computer Science
Hitec University
Taxila Cantt
Pakistan

2.1a: Flynn’s Classical Taxonomy
2
One of the more widely used parallel computer
classifications, since 1966, is called Flynn’s Taxonomy
It distinguishes multiprocessor computers according to
the dimensions of Instruction and Data
 SISD: Single instruction stream, Single data stream
 SIMD: Single instruction stream, Multiple data streams
 MISD: Multiple instruction streams, Single data stream
 MIMD: Multiple instruction streams, Multiple data
streams

2.1b: SISD Machines
 A serial (non-parallel) computer
 Single instruction: Only one instruction
stream is acted on by CPU during any one
clock cycle
 Single data: Only one data stream is used
as input during any one clock cycle
 Deterministic execution
 Oldest and most prevalent form computer
 Examples: Most PCs, single CPU
workstations and mainframes
3

2.2a: SIMD Machines (I)
4
 A type of parallel computers
 Single instruction: All processor units execute the same
instruction at any give clock cycle
 Multiple data: Each processing unit can operate on a different
data element
 It typically has an instruction dispatcher, a very high-bandwidth
internal network, and a very large array of very small-capacity
instruction units
 Best suitable for specialized problems characterized by a high
degree of regularity, e.g., image processing
 Two varieties: Processor Arrays and Vector Pipelines
 Examples: Connection Machines, MasPar-1, MasPar-2;
 IBM 9000, Cray C90, Fujitsu VP, etc

Pipelined Processing
 A pipeline, also known as a data pipeline,
 is a set of data processing elements connected in series,
 where the output of one element is the input of the next
one.
 The elements of a pipeline are often executed in parallel or
in time-sliced fashion
 A category of techniques that provide simultaneous, or
parallel, processing within the computer.
 It refers to overlapping operations by moving data or
instructions into a conceptual pipe with all stages of the
pipe processing simultaneously.
8

2.2f: Pipelined Processing
A six-step pipeline with
IEEE arithmetic hardware
Parallelization happens
behind the scene
Not true parallel
computers
9

Assembly Line
 An assembly line is a manufacturing process in which
parts are added as the semi-finished assembly moves from
workstation to workstation where the parts are added in
sequence until the final assembly is produced
10

Vector Processor Pipeline
 The term "vector pipeline" was used in the 1970's to
describe vector processing at a time when a single vector
instruction might (for example) compute the sum of two
vectors of floating point numbers using a single pipelined
floating point arithmetic unit
12

2.2h: Vector Processor Pipeline
13

2.3a: MISD Machines (I)
14
 A single data stream is fed into multiple
processing units
 Each processing unit operates on the data
independently via independent instruction
streams
 Very few actual machines: CMU’s C.mmp
computer (1971)
 Possible use: multiple frequency filters
operating on a single signal stream

2.4a: MIMD Machines (I)
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 Multiple instruction: Every processor may
execute a different instruction stream
 Multiple data: Every processor may work with
a different data stream
 Execution can be synchronous or
asynchronous, deterministic or non-
deterministic
 Examples: most current supercomputers,
grids, networked parallel computers,
multiprocessor SMP computer

T3E-Cray
19
 The Cray T3E was Cray Research's
second-generation massively parallel
supercomputer architecture, launched in
late November 1995. ... Like the previous
Cray T3D, it was a fully distributed
memory machine using a 3D torus
topology interconnection network.

2.4d: MIMD Machines (T3E-Cray)
20

2.5: Shared Memory and Message Passing
21
 Parallel computers can also be classified
according to memory access
 Shared memory computers
 Message-passing (distributed memory)
computers
 Multi-processor computers
 Multi-computers
 Clusters
 Grids

2.6a: Shared Memory Computers
22
 All processors have access to all memory as
a global address space
 Multiple processors can operate
independently, but share the same memory
resources
 Changes in a memory location effected by
one processor are visible to all other
processors
 Two classes of shared memory machines:
UMA and NUMA, (and COMA)

2.6b: Shared Memory Architecture
23

2.6c: Uniform Memory Access (UMA)
24
 Most commonly represented today by Symmetric
Multiprocessor (SMP) machines
 Identical processors
 Equal access and access time to memory
 Sometimes called CC-UMA – Cache Coherent UMA
 Cache Coherence:
If one processor updates a location in shared
memory, all the other processors know about the
update. Cache coherence is accomplished at the
hardware level

2.6d: Symmetric Multiprocessor (SMP)
25

2.6e: UMA –with and without caches
26

2.6f: Nonuniform Memory Access
(NUMA)
27
 Often made by physically linked two or more
SMPs
 One SMP can directly access memory of
another SMP
 Not all processors have equal access time to
all memories
 Memory access across link is slower
 If cache coherence is maintained, they may
also be called CC-NUMA

2.6h: Hybrid Machine (UMA & NUMA)
29

2.6i: Advantages of Shared Memory
Machines
30
 Global address space provides a
user-friendly programming
environment to memory access
 Data sharing between tasks is
both fast and uniform due to
proximity of memory to CPUs

2.6j: Disadvantages of Shared Memory
Machines
31
 Lack of scalability between memory and
CPUs: Adding processors can geometrically
increase traffic on the shared memory-CPU
path and for cache coherence management
 Programmer’s responsibility for
synchronization constructs (correct access to
memory)
 Expensive to design shared memory
computers with increasing numbers of
processors

2.7a: Distributed Memory Computers
32
 Processors have their own local memory
 It requires a communication network to connect
inter-processor memory
 Memory addresses in one processor do not map to
another processor – no concept of global address
space across all processors
 The concept of cache coherence does not apply
 Data are exchanged explicitly through message-
passing
 Synchronization between tasks is the programmer’s
responsibility

2.7b: Distributed Memory Architecture
33

2.7c: Advantages of Distributed Memory
Machines
34
 Memory is scalable with the number of processors
 Increase the number of processors, the size of
memory increases proportionally
 Each processor can rapidly access its own memory
without interference and without the overhead
incurred with trying to maintain cache coherence
 Cost effectiveness: can use commodity, off-the-
shelf processors and networking

2.7d: Disadvantages of Distributed
Memory Machines
35
 Difficult to program: Programmer has to
handle data communication between
processors
 Nonuniform memory access (NUMA) times
 It may be difficult to map existing data
structures, based on global memory, to
distributed memory organization

2.7e: Networked Cluster of Workstatsions
(PCs)
36

2.7f: Massively Parallel Processing (MPP)
Environment
37

2.7g: Distributed Shared Memory (DSM)
Computer
38

2.7h: Hybrid and Combinations (Very
Large Parallel Computing System)
39

2.8: Architectural Design Tradeoffs
40
Shared
memory
Distributed
memory
Programmability easier harder
Scalability harder easier

2.9:Parallel Architectural Issues
41
 Control mechanism: SIMD vs MIMD
 Operation: synchronous vs asynchronous
 Memory organization: private vs shared
 Address space: local vs global
 Memory access: uniform vs nonuniform
 Granularity: power of individual processors
coarse grained system vs fine grained system
 Interconnection network topology

2.10a: Beowulf Cluster System
42
 A cluster of tightly coupled PC’s for distributed
parallel computation
 Moderate size: normally 16 to 32 PC’s
 Promise of good price/performance ratio
 Use of commodity-of-the-self (COTS) components
(PCs, Linux, MPI)
 Initiated at NASA (Center of Excellence in Space
Data and Information Sciences) in 1994 using 16
DX4 processors
 http://www.beowulf.org

2.10b: NASA 128-Processor Beowulf
Cluster
43

2.11a: Sun Enterprise 10000 Server (I)
44
 Starfire is a shared-address space machine
4 to 64 processors, each is an UltraSPARC II
running at 400 MHz with a peak rate 800 MHz
 System board has up to 4 CPUs and 4GB RAM
local memory
 Up to 64 GB memory in total
 16 such boards can be connected via a Gigaplane-
XB interconnect

2.11b: Sun Enterprise 10000 Server (II)
45
 Intra- and inter-board connectivity uses
different interconnection networks
 Intra-board connectivity is by a split
transaction system bus (Gigaplane bus)
 Global data router is a 16X16 non-blocking
crossbar for the data buses and four global
address buses
 http://www.sun.com/servers/highend/e10000/

2.11c: Sun Enterprise 10000 Server (III)
46

2.11d: Sun Enterprise 10000 Server (IV)
47

2.12a: SGI Origin Servers (I)
48
 SGI Origin 3000 Servers support up to 512
MPIS 14000 processors in a NUMA cache
coherent shared-address-space configuration
 Each processor operates at 500 MHz with a
peak rate of 1.0 gigaflops
 Modular framework with 4 CPUs and 8GB of
RAM (C-Brick)
 Interconnection by crossbar between C-
Bricks and R-Bricks (routers)

2.12b: SGI Origin Servers (II)
49
 Larger configuration are built by connecting
multiple C-Bricks via R-Bricks using 6-port or
8-port crossbar switches and metarouters
with full-duplex links operating at 1.6GB/s
 http://www.sgi.com/products/servers/origin/30
00/overview.html

2.12c: C-Brick and R-Brick
C- Brick
50
R- Brick

2.12e: SGI Origin Server Machine
52

2.13a: Cray T3E/1350
53
 Use Alpha 21164A processor with 4-way
superscalar architecture, 2 floating point instruction
per cycle
 CPU clock 675 MHz, with peak rating 1.35
Gigaflops, 512 MB local memory
 Parallel systems with 40 to 2176 processors (with
modules of 8 CPUs each)
 3D torus interconnect with a single processor per
node
 Each node contains a router and has a processor
interface and six full-duplex link (one for each
direction of the cube)

2.14a: UK HP Superdome Cluster
56
 4 HP superdomes
 256 total processors (64 processors per
host/node)
 Itanium-2 processor at 1.6 TF peak rate
 2 GB memory per processor
 7 Terabytes of total disk space
 High speed, low latency Infiniband internal
interconnect

2.14b: HP Superdome Cluster
57

2.15a: The Earth Simulator (I)
58
 Each processor of the Earth Simulator runs at
2ns per cycle, with 16GB shared memory
 Total number of processors is 5,120. The
aggregated peak performance is 40 TFlops
with 10 TB memory
 It has a single stage crossbar (1800 miles of
cable), 83,000 copper cables, 16 GB/s cross
station bandwidth
 700 TB disk space and 1.6PB mass storage

2.15b: The Earth Simulator (II)
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 One node = 8 vector processors with a peak
performance of 8G Flops (640X8 = 5,120)
 Area of the computer = 4 tennis courts, 3
floors
 Sum of all the US Department
supercomputers = 24 TFlops/s in 2002
 Number 1 in 2002 top 500 list (five
consecutive lists)
 http://www.es.jamstec.go.jp/esc/eng/

2.15c: The Earth Simulator Machine (I)
60

2.15d: The Earth Simulator Machine (II)
61

2.16a: IBM Blue Gene (I)
62
 In December 1999, IBM Research
announced a 5-year $100M project, named
Blue Gene, to develop a petaflop computer
for research in computational biology
 Proposed architecture: SMASH (simple,
multiple, self-healing)
 Collaboration between IBM Thomas J.
Watson Research Center, Lawrence
Livermore National Laboratory, US DOE and
academia

2.16b: IBM Blue Gene (II)
63
 1 million CPUs of 1 gigflop each = 1 petaflop
 32 CPUs on a single chip, 16 MB memory
 64 chips are placed on a board of 20 inches
 8 boards form a tower, and 64 towers are connected
into a 8X8 grid to form Blue Gene
 Blue Gene/L, Blue Gene/C, and Blue Gene/P for
different applications
 # 1 and # 2 on top 500 list in December 2005
 http://domino.research.ibm.com/comm/research_pro
jects.nsf/pages/bluegene.index.html

2.17a: Current Number 1 (Blue Gene/L)
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 eServer Blue Gene Solution (Blue Gene/L)
 32,768 GB memory
 Installed in 2005 DOE/NNSA/LLNL
 131,072 processors
 Peak performance 367.8 TFlops, 280.6 Tflops/s
LINPACK benchmark
 See more at http://www.top500.org
 The Earth Simulator is currently # 10
 Next round announcement: November 2006,
Tampa, Florida at Supercomputing 2006

2.18a: The Really Fastest One
66
 On June 26, 2006, MD-Grape-3 at Riken in Japan,
clocked at 1.0 petaflop. But it does not run LINPACK
and not qualify for top 500 list
 Special purpose system for molecular dynamics – 3
times faster than Blue Gene/L
 201 units of 24 custom MDGrape-3 chips (4808
total), plus 64 servers each with 256 Dual-Core Intel
Xeon processor, and 37 servers each containing 74
Intel 3.2 GHz Xeon processors
 http://www.primidi.com/2004/09/01.html

2.18c: One Board with 12 MDGrape-3
Chips
68

Lecture 04 chapter 2 - Parallel Programming Platforms

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