Pipelining (I) Notes | EduRev

Created by: Sanya Gill

: Pipelining (I) Notes | EduRev

 Page 1


CSCI-0310 
CSCI-0310 
 Pascal Van Hentenryck 
1 
Memory Hierarchy 
Lecture 22 
Page 2


CSCI-0310 
CSCI-0310 
 Pascal Van Hentenryck 
1 
Memory Hierarchy 
Lecture 22 
CSCI-0310 
2 
Memory Hierarchy 
•? Memory hierarchy 
•? Caches 
•? Buses 
Lecture 22 
Page 3


CSCI-0310 
CSCI-0310 
 Pascal Van Hentenryck 
1 
Memory Hierarchy 
Lecture 22 
CSCI-0310 
2 
Memory Hierarchy 
•? Memory hierarchy 
•? Caches 
•? Buses 
Lecture 22 
CSCI-0310 
3 
Memory Hierarchy 
We would like to create an illusion 
that the processor has large amounts 
of very fast memory connected to it. 
It needs to be an illusion because fast 
memory is expensive 
Technology Access Time $ per Mbyte 
SRAM 8 - 35 ns 3.00 
DRAM 90 - 120 ns 1.00 
Magnetic Disk 10,000,000 ns 0.0000001 
Lecture 22 
Page 4


CSCI-0310 
CSCI-0310 
 Pascal Van Hentenryck 
1 
Memory Hierarchy 
Lecture 22 
CSCI-0310 
2 
Memory Hierarchy 
•? Memory hierarchy 
•? Caches 
•? Buses 
Lecture 22 
CSCI-0310 
3 
Memory Hierarchy 
We would like to create an illusion 
that the processor has large amounts 
of very fast memory connected to it. 
It needs to be an illusion because fast 
memory is expensive 
Technology Access Time $ per Mbyte 
SRAM 8 - 35 ns 3.00 
DRAM 90 - 120 ns 1.00 
Magnetic Disk 10,000,000 ns 0.0000001 
Lecture 22 
CSCI-0310 
4 
Principle of Locality 
Memory references in programs tend to 
obey these principles: 
Temporal locality: If an item is referenced, it 
will tend to be referenced again soon. 
Spatial locality: If an item is referenced, 
items whose addresses are close by will 
tend to be referenced soon. 
Analogy: your use of web pages. 
Lecture 22 
Page 5


CSCI-0310 
CSCI-0310 
 Pascal Van Hentenryck 
1 
Memory Hierarchy 
Lecture 22 
CSCI-0310 
2 
Memory Hierarchy 
•? Memory hierarchy 
•? Caches 
•? Buses 
Lecture 22 
CSCI-0310 
3 
Memory Hierarchy 
We would like to create an illusion 
that the processor has large amounts 
of very fast memory connected to it. 
It needs to be an illusion because fast 
memory is expensive 
Technology Access Time $ per Mbyte 
SRAM 8 - 35 ns 3.00 
DRAM 90 - 120 ns 1.00 
Magnetic Disk 10,000,000 ns 0.0000001 
Lecture 22 
CSCI-0310 
4 
Principle of Locality 
Memory references in programs tend to 
obey these principles: 
Temporal locality: If an item is referenced, it 
will tend to be referenced again soon. 
Spatial locality: If an item is referenced, 
items whose addresses are close by will 
tend to be referenced soon. 
Analogy: your use of web pages. 
Lecture 22 
CSCI-0310 
5 
Memory Hierarchy 
We’ll use a hierarchy of memory modules to 
maintain the illusion 
CPU 
Expensive 
Memory 
Memory (RAM) 
Cheap 
Memory 
(Disk) 
Fastest 
Slowest 
Smallest 
Biggest 
Lecture 22 
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