High Performance Computing
Lecture 34
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Understanding Program Behaviour - High Performance Computing - Lecture Slides, Slides of Computer Science
Some concept of High Performance Computing are Addressing Modes, Program Execution, Basic Computer Organization, Control Hazard Solutions, Least Recently Used, Memory Hierarchy Progression. Main points of this lecture are: Understanding Program Behaviour, Profiling, Important Parts, Learned, Involved, Computer System, Considered, Silicon Memory, Implementing Registers, Flip-Flop
Typology: Slides
2012/2013
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High Performance Computing
Lecture 34
2
Understanding Program Behaviour
Profiling: We have seen how to learn more
about the important parts of our programs
to concentrate our optimization efforts there
Earlier, we learned about the hardware and
software that are involved in making our
program execute on a computer system
There are (at least) 2 problems with this that
we had not considered
4
2. Problem with How Programs Execute
% a.out
Program runs as a process
Memory image made up of text, data, stack
and heap
But that all disappears when the program
finishes executing
5
Recall: Lifetime of Data
1. Lifetime = Execution time of program
2. Lifetime = Time between explicit creation of
data & explicit deletion of data
3. Lifetime = During execution of a function
(i.e., time between function call and return)
4. Lifetime = Beyond the execution time of the
program
- even if the power fails while the program is
running
7
What is a File?
1. Storage for data that continues to exist
beyond the lifetime of program
Persistent data
This will be possible only through the use of non-
volatile, persistent secondary storage devices
like hard disk
2. A named sequence of data on a persistent
storage device
8
Secondary Storage
Today, there are 3 main kinds
1. Magnetic: information stored on magnetic
medium
e.g., hard disk drive, floppy disk, mag tape cartridge
2. Optical: information stored by optical
properties
e.g., CD, DVD
3. Flash: information stored like in RAM cell,
but with very slow rate of leakage
e.g., memory stick
10
About Disks
Platter: rotating metal disk covered with magnetic material Side view of a platter Spindle on which the platter rotates
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About Disks
Track: concentric circular recording surface Top view of a platter Innermost track Outermost track
13
About Disks
Read/write head: An electromagnet that is used to read/write a sector Top view of a platter Read/write head Arm
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About Disks
Multiple platters rotating together on a common spindle Side view of a disk with multiple platters Magnetic coating possibly on both upper and lower surfaces of platters
16
About Disks
Cylinder: all the tracks associated with a given actuator position Current cylinder: Outermost track of each surface If the actuator then moves the heads in completely…
17
About Disks
Cylinder: all the tracks associated with a given actuator position Current cylinder: Innermost track of each surface