Cache memory is a small, fast memory located close to the processor that stores frequently accessed data from main memory. When the processor requests data, the cache is checked first. If the data is present, there is a cache hit and the data is accessed quickly from the cache. If not present, there is a cache hit and the data must be fetched from main memory, which takes longer. Cache memory relies on principles of temporal and spatial locality, where frequently and nearby accessed data is likely to be needed again soon. Mapping functions like direct, associative, and set-associative mapping determine how data is stored in the cache. Replacement policies like FIFO, LRU, etc. determine which cached data gets replaced when new
Cache memory is a small, fast memory located close to the CPU that stores frequently accessed instructions and data. It aims to bridge the gap between the fast CPU and slower main memory. Cache memory is organized into blocks that each contain a tag field identifying the memory address, a data field containing the cached data, and status bits. There are different mapping techniques like direct mapping, associative mapping, and set associative mapping to determine how blocks are stored in cache. When cache is full, replacement algorithms like LRU, FIFO, LFU, and random are used to determine which existing block to replace with the new block.
Cache memory is a small amount of fast SRAM located between the CPU and main memory that stores frequently accessed data. When the CPU requests data, the cache memory is checked first and if the data is present it can be accessed much faster than main memory. If the data is not in cache memory, it is retrieved from main memory which is slower but larger DRAM. Modern processors use a multi-level cache system with multiple cache levels (L1, L2, etc.) checked sequentially to improve performance.
Cache memory is a small, fast memory located between the CPU and main memory that stores copies of frequently used instructions and data. It accelerates computer speed while keeping costs low. When the CPU requests data, the cache is checked first for a cache hit before accessing the slower main memory. If the data is not found in cache, a cache miss occurs and the data must be retrieved from main memory, which is slower. Replacement algorithms like LRU determine which cached data to replace when new data must be added to a full cache.
This document discusses various aspects of computer memory systems including cache memory. It begins by defining key terms related to memory such as capacity, organization, access methods, and physical characteristics. It then covers cache memory in particular, explaining the basic concept of caching as well as aspects of cache design like mapping, replacement algorithms, and write policies. Examples of cache configurations from different processor models over time are also provided.
The document discusses cache memory and provides information on various aspects of cache memory including:
- Introduction to cache memory including its purpose and levels.
- Cache structure and organization including cache row entries, cache blocks, and mapping techniques.
- Performance of cache memory including factors like cycle count and hit ratio.
- Cache coherence in multiprocessor systems and coherence protocols.
- Synchronization mechanisms used in multiprocessor systems for cache coherence.
- Paging techniques used in cache memory including address translation using page tables and TLBs.
- Replacement algorithms used to determine which cache blocks to replace when the cache is full.
Cache memory is a small, fast memory located between the CPU and main memory. It stores copies of frequently used instructions and data to accelerate access and improve performance. There are different mapping techniques for cache including direct mapping, associative mapping, and set associative mapping. When the cache is full, replacement algorithms like LRU and FIFO are used to determine which content to remove. The cache can write to main memory using either a write-through or write-back policy.
Cache memory is a small, fast memory located between the CPU and main memory that temporarily stores frequently accessed data. It improves performance by providing faster access for the CPU compared to accessing main memory. There are different types of cache memory organization including direct mapping, set associative mapping, and fully associative mapping. Direct mapping maps each block of main memory to only one location in cache while set associative mapping divides the cache into sets with multiple lines per set allowing a block to map to any line within a set.
Cache memory is a small, fast memory located close to the CPU that stores frequently accessed instructions and data. It aims to bridge the gap between the fast CPU and slower main memory. Cache memory is organized into blocks that each contain a tag field identifying the memory address, a data field containing the cached data, and status bits. There are different mapping techniques like direct mapping, associative mapping, and set associative mapping to determine how blocks are stored in cache. When cache is full, replacement algorithms like LRU, FIFO, LFU, and random are used to determine which existing block to replace with the new block.
Cache memory is a small amount of fast SRAM located between the CPU and main memory that stores frequently accessed data. When the CPU requests data, the cache memory is checked first and if the data is present it can be accessed much faster than main memory. If the data is not in cache memory, it is retrieved from main memory which is slower but larger DRAM. Modern processors use a multi-level cache system with multiple cache levels (L1, L2, etc.) checked sequentially to improve performance.
Cache memory is a small, fast memory located between the CPU and main memory that stores copies of frequently used instructions and data. It accelerates computer speed while keeping costs low. When the CPU requests data, the cache is checked first for a cache hit before accessing the slower main memory. If the data is not found in cache, a cache miss occurs and the data must be retrieved from main memory, which is slower. Replacement algorithms like LRU determine which cached data to replace when new data must be added to a full cache.
This document discusses various aspects of computer memory systems including cache memory. It begins by defining key terms related to memory such as capacity, organization, access methods, and physical characteristics. It then covers cache memory in particular, explaining the basic concept of caching as well as aspects of cache design like mapping, replacement algorithms, and write policies. Examples of cache configurations from different processor models over time are also provided.
The document discusses cache memory and provides information on various aspects of cache memory including:
- Introduction to cache memory including its purpose and levels.
- Cache structure and organization including cache row entries, cache blocks, and mapping techniques.
- Performance of cache memory including factors like cycle count and hit ratio.
- Cache coherence in multiprocessor systems and coherence protocols.
- Synchronization mechanisms used in multiprocessor systems for cache coherence.
- Paging techniques used in cache memory including address translation using page tables and TLBs.
- Replacement algorithms used to determine which cache blocks to replace when the cache is full.
Cache memory is a small, fast memory located between the CPU and main memory. It stores copies of frequently used instructions and data to accelerate access and improve performance. There are different mapping techniques for cache including direct mapping, associative mapping, and set associative mapping. When the cache is full, replacement algorithms like LRU and FIFO are used to determine which content to remove. The cache can write to main memory using either a write-through or write-back policy.
Cache memory is a small, fast memory located between the CPU and main memory that temporarily stores frequently accessed data. It improves performance by providing faster access for the CPU compared to accessing main memory. There are different types of cache memory organization including direct mapping, set associative mapping, and fully associative mapping. Direct mapping maps each block of main memory to only one location in cache while set associative mapping divides the cache into sets with multiple lines per set allowing a block to map to any line within a set.
About Cache Memory
working of cache memory
levels of cache memory
mapping techniques for cache memory
1. direct mapping techniques
2. Fully associative mapping techniques
3. set associative mapping techniques
Cache memroy organization
cache coherency
every thing in detail
This document contains information about cache memory provided by multiple students:
- Cache memory is a fast type of volatile memory that stores frequently used data and programs to provide faster access for the CPU. It stores data temporarily until the computer is powered off.
- There are different levels of cache memory with L1 cache being the fastest and closest to the CPU. Cache mapping determines how data is stored in cache memory and there are three main types: direct mapping, associative mapping, and set associative mapping.
- When data is replaced in cache memory, different replacement algorithms are used to determine which data to remove. Write policies like write-through and write-back determine when written data is transferred from cache to main
This document discusses memory organization and virtual memory. It describes paging and segmentation as methods for virtual memory address translation. Paging divides memory and processes into equal sized pages, while segmentation divides processes into variable sized segments. Both methods use data structures like page tables to map logical addresses to physical addresses. Caching is also discussed as a way to improve memory performance by storing frequently accessed data in a small, fast memory near the CPU.
The document discusses memory management techniques used in operating systems. It describes logical vs physical addresses and how relocation registers map logical addresses to physical addresses. It covers contiguous and non-contiguous storage allocation, including paging and segmentation. Paging divides memory into fixed-size frames and pages, using a page table and translation lookaside buffer (TLB) for address translation. Segmentation divides memory into variable-sized segments based on a program's logical structure. Virtual memory and demand paging are also covered, along with page replacement algorithms like FIFO, LRU and optimal replacement.
Operating System
Topic Memory Management
for Btech/Bsc (C.S)/BCA...
Memory management is the functionality of an operating system which handles or manages primary memory. Memory management keeps track of each and every memory location either it is allocated to some process or it is free. It checks how much memory is to be allocated to processes. It decides which process will get memory at what time. It tracks whenever some memory gets freed or unallocated and correspondingly it updates the status.
This document discusses the key characteristics of computer memory, including location, capacity, unit of transfer, access methods, performance, physical type, physical characteristics, and organization. It covers different types of memory like CPU registers, main memory, cache, disk, and tape. The different access methods like sequential, direct, random, and associative access are explained. The memory hierarchy and performance aspects like access time, memory cycle time, and transfer rate are defined. Factors like cache size, mapping function, replacement algorithm, write policy, block size that impact cache performance are also summarized.
The document discusses various types of computer memory technologies, including RAM types like DRAM, SRAM, DDR, DDR2, and DDR3. It explains the memory hierarchy from registers to cache to main memory to disks. Key points covered include how DRAM works using capacitors that must be periodically refreshed, advantages of SDRAM over regular DRAM like pipelining commands. Generations of DDR memory are compared in terms of clock speeds, data rates, and other features.
This presentation describes about the various memory allocation methods like first fit, best fit and worst fit in memory management and also about fragmentation problem and solution for the problem.
Virtual memory allows a program to use more memory than the physical RAM installed on a computer. It works by storing portions of programs and data that are not actively being used on the hard disk, freeing up RAM for active portions. This gives the illusion to the user and programs that they have access to more memory than is physically present. Virtual memory provides advantages like allowing more programs to run at once and not requiring additional RAM purchases, but can reduce performance due to the need to access the hard disk.
The document discusses the concept of virtual memory. Virtual memory allows a program to access more memory than what is physically available in RAM by storing unused portions of the program on disk. When a program requests data that is not currently in RAM, it triggers a page fault that causes the needed page to be swapped from disk into RAM. This allows the illusion of more memory than physically available through swapping pages between RAM and disk as needed by the program during execution.
Memory organization in computer architectureFaisal Hussain
Memory organization in computer architecture
Volatile Memory
Non-Volatile Memory
Memory Hierarchy
Memory Access Methods
Random Access
Sequential Access
Direct Access
Main Memory
DRAM
SRAM
NVRAM
RAM: Random Access Memory
ROM: Read Only Memory
Auxiliary Memory
Cache Memory
Hit Ratio
Associative Memory
The Presentation introduces the basic concept of cache memory, its introduction , background and all necessary details are provided along with details of different mapping techniques that are used inside Cache Memory.
This document discusses cache memory organization and characteristics. It begins by describing cache location, capacity, unit of transfer, access methods, and physical characteristics. It then covers the different mapping techniques used in caches, including direct mapping, set associative mapping, and fully associative mapping. The document also discusses cache performance factors like hit ratio, replacement algorithms, write policies, block size, and multilevel cache hierarchies. It provides examples of specific processor cache designs like those used in Intel Pentium processors.
Virtual memory allows programs to execute without requiring their entire address space to be resident in physical memory. It uses virtual addresses that are translated to physical addresses by the hardware. This translation occurs via page tables managed by the operating system. When a virtual address is accessed, its virtual page number is used as an index into the page table to obtain the corresponding physical page frame number. If the page is not in memory, a page fault occurs and the OS handles loading it from disk. Paging partitions both physical and virtual memory into fixed-sized pages to address fragmentation issues. Segmentation further partitions the virtual address space into logical segments. Hardware support for segmentation involves a segment table containing base/limit pairs for each segment. Translation lookaside buffers
The document discusses the memory system in computers including main memory, cache memory, and different types of memory chips. It provides details on the following key points in 3 sentences:
The document discusses the different levels of memory hierarchy including main memory, cache memory, and auxiliary memory. It describes the basic concepts of memory including addressing schemes, memory access time, and memory cycle time. Examples of different types of memory chips are discussed such as SRAM, DRAM, ROM, and cache memory organization and mapping techniques.
Virtual memory allows a program to access more memory than is physically installed on the system by storing seldom-used data on disk. The CPU uses virtual addresses while physical addresses identify the actual memory location. The memory management unit (MMU) translates virtual to physical addresses using page tables stored in memory. If a page is not in memory, a page fault occurs and the OS loads the required page from disk before resuming execution. Virtual memory provides the illusion of a larger memory to programs through demand paged paging and address translation mechanisms.
A memory unit contains storage devices that store binary information as bits. Memory can be classified as volatile, which loses data when power is off, or non-volatile, which retains data when unpowered. The total computer memory forms a hierarchy from slow auxiliary memory to faster main memory and cache memory. Main memory communicates directly with the CPU and auxiliary memory, and holds programs currently in use while transferring unused programs to auxiliary memory. Memory can be accessed randomly, sequentially, or directly depending on its type.
Direct memory access (DMA) allows certain hardware subsystems to access computer memory independently of the central processing unit (CPU). During DMA transfer, the CPU is idle while an I/O device reads from or writes directly to memory using a DMA controller. This improves data transfer speeds as the CPU does not need to manage each memory access and can perform other tasks. DMA is useful when CPU cannot keep up with data transfer speeds or needs to work while waiting for a slow I/O operation to complete.
The document discusses CPU caching concepts including the need for caching due to the gap between CPU and memory speeds and the principle of locality of reference. It describes cache hierarchy with different levels (L1, L2, L3 caches) and cache organization involving mapping of memory blocks to cache blocks. The document also covers cache operations of hits and misses as well as handling cache misses through replacement policies and ensuring cache coherence through protocols.
The document discusses CPU caching concepts. It explains that caches are faster but smaller memories that store copies of frequently accessed data from main memory, due to principles of locality of reference and the speed gap between CPUs and memory. The document outlines cache hierarchy levels, organization, mapping techniques, handling cache misses through replacement policies, updating policies for writes, issues of stale data, and modern research areas like cache coherence for multicore CPUs.
About Cache Memory
working of cache memory
levels of cache memory
mapping techniques for cache memory
1. direct mapping techniques
2. Fully associative mapping techniques
3. set associative mapping techniques
Cache memroy organization
cache coherency
every thing in detail
This document contains information about cache memory provided by multiple students:
- Cache memory is a fast type of volatile memory that stores frequently used data and programs to provide faster access for the CPU. It stores data temporarily until the computer is powered off.
- There are different levels of cache memory with L1 cache being the fastest and closest to the CPU. Cache mapping determines how data is stored in cache memory and there are three main types: direct mapping, associative mapping, and set associative mapping.
- When data is replaced in cache memory, different replacement algorithms are used to determine which data to remove. Write policies like write-through and write-back determine when written data is transferred from cache to main
This document discusses memory organization and virtual memory. It describes paging and segmentation as methods for virtual memory address translation. Paging divides memory and processes into equal sized pages, while segmentation divides processes into variable sized segments. Both methods use data structures like page tables to map logical addresses to physical addresses. Caching is also discussed as a way to improve memory performance by storing frequently accessed data in a small, fast memory near the CPU.
The document discusses memory management techniques used in operating systems. It describes logical vs physical addresses and how relocation registers map logical addresses to physical addresses. It covers contiguous and non-contiguous storage allocation, including paging and segmentation. Paging divides memory into fixed-size frames and pages, using a page table and translation lookaside buffer (TLB) for address translation. Segmentation divides memory into variable-sized segments based on a program's logical structure. Virtual memory and demand paging are also covered, along with page replacement algorithms like FIFO, LRU and optimal replacement.
Operating System
Topic Memory Management
for Btech/Bsc (C.S)/BCA...
Memory management is the functionality of an operating system which handles or manages primary memory. Memory management keeps track of each and every memory location either it is allocated to some process or it is free. It checks how much memory is to be allocated to processes. It decides which process will get memory at what time. It tracks whenever some memory gets freed or unallocated and correspondingly it updates the status.
This document discusses the key characteristics of computer memory, including location, capacity, unit of transfer, access methods, performance, physical type, physical characteristics, and organization. It covers different types of memory like CPU registers, main memory, cache, disk, and tape. The different access methods like sequential, direct, random, and associative access are explained. The memory hierarchy and performance aspects like access time, memory cycle time, and transfer rate are defined. Factors like cache size, mapping function, replacement algorithm, write policy, block size that impact cache performance are also summarized.
The document discusses various types of computer memory technologies, including RAM types like DRAM, SRAM, DDR, DDR2, and DDR3. It explains the memory hierarchy from registers to cache to main memory to disks. Key points covered include how DRAM works using capacitors that must be periodically refreshed, advantages of SDRAM over regular DRAM like pipelining commands. Generations of DDR memory are compared in terms of clock speeds, data rates, and other features.
This presentation describes about the various memory allocation methods like first fit, best fit and worst fit in memory management and also about fragmentation problem and solution for the problem.
Virtual memory allows a program to use more memory than the physical RAM installed on a computer. It works by storing portions of programs and data that are not actively being used on the hard disk, freeing up RAM for active portions. This gives the illusion to the user and programs that they have access to more memory than is physically present. Virtual memory provides advantages like allowing more programs to run at once and not requiring additional RAM purchases, but can reduce performance due to the need to access the hard disk.
The document discusses the concept of virtual memory. Virtual memory allows a program to access more memory than what is physically available in RAM by storing unused portions of the program on disk. When a program requests data that is not currently in RAM, it triggers a page fault that causes the needed page to be swapped from disk into RAM. This allows the illusion of more memory than physically available through swapping pages between RAM and disk as needed by the program during execution.
Memory organization in computer architectureFaisal Hussain
Memory organization in computer architecture
Volatile Memory
Non-Volatile Memory
Memory Hierarchy
Memory Access Methods
Random Access
Sequential Access
Direct Access
Main Memory
DRAM
SRAM
NVRAM
RAM: Random Access Memory
ROM: Read Only Memory
Auxiliary Memory
Cache Memory
Hit Ratio
Associative Memory
The Presentation introduces the basic concept of cache memory, its introduction , background and all necessary details are provided along with details of different mapping techniques that are used inside Cache Memory.
This document discusses cache memory organization and characteristics. It begins by describing cache location, capacity, unit of transfer, access methods, and physical characteristics. It then covers the different mapping techniques used in caches, including direct mapping, set associative mapping, and fully associative mapping. The document also discusses cache performance factors like hit ratio, replacement algorithms, write policies, block size, and multilevel cache hierarchies. It provides examples of specific processor cache designs like those used in Intel Pentium processors.
Virtual memory allows programs to execute without requiring their entire address space to be resident in physical memory. It uses virtual addresses that are translated to physical addresses by the hardware. This translation occurs via page tables managed by the operating system. When a virtual address is accessed, its virtual page number is used as an index into the page table to obtain the corresponding physical page frame number. If the page is not in memory, a page fault occurs and the OS handles loading it from disk. Paging partitions both physical and virtual memory into fixed-sized pages to address fragmentation issues. Segmentation further partitions the virtual address space into logical segments. Hardware support for segmentation involves a segment table containing base/limit pairs for each segment. Translation lookaside buffers
The document discusses the memory system in computers including main memory, cache memory, and different types of memory chips. It provides details on the following key points in 3 sentences:
The document discusses the different levels of memory hierarchy including main memory, cache memory, and auxiliary memory. It describes the basic concepts of memory including addressing schemes, memory access time, and memory cycle time. Examples of different types of memory chips are discussed such as SRAM, DRAM, ROM, and cache memory organization and mapping techniques.
Virtual memory allows a program to access more memory than is physically installed on the system by storing seldom-used data on disk. The CPU uses virtual addresses while physical addresses identify the actual memory location. The memory management unit (MMU) translates virtual to physical addresses using page tables stored in memory. If a page is not in memory, a page fault occurs and the OS loads the required page from disk before resuming execution. Virtual memory provides the illusion of a larger memory to programs through demand paged paging and address translation mechanisms.
A memory unit contains storage devices that store binary information as bits. Memory can be classified as volatile, which loses data when power is off, or non-volatile, which retains data when unpowered. The total computer memory forms a hierarchy from slow auxiliary memory to faster main memory and cache memory. Main memory communicates directly with the CPU and auxiliary memory, and holds programs currently in use while transferring unused programs to auxiliary memory. Memory can be accessed randomly, sequentially, or directly depending on its type.
Direct memory access (DMA) allows certain hardware subsystems to access computer memory independently of the central processing unit (CPU). During DMA transfer, the CPU is idle while an I/O device reads from or writes directly to memory using a DMA controller. This improves data transfer speeds as the CPU does not need to manage each memory access and can perform other tasks. DMA is useful when CPU cannot keep up with data transfer speeds or needs to work while waiting for a slow I/O operation to complete.
The document discusses CPU caching concepts including the need for caching due to the gap between CPU and memory speeds and the principle of locality of reference. It describes cache hierarchy with different levels (L1, L2, L3 caches) and cache organization involving mapping of memory blocks to cache blocks. The document also covers cache operations of hits and misses as well as handling cache misses through replacement policies and ensuring cache coherence through protocols.
The document discusses CPU caching concepts. It explains that caches are faster but smaller memories that store copies of frequently accessed data from main memory, due to principles of locality of reference and the speed gap between CPUs and memory. The document outlines cache hierarchy levels, organization, mapping techniques, handling cache misses through replacement policies, updating policies for writes, issues of stale data, and modern research areas like cache coherence for multicore CPUs.
This document provides an overview of cache memory, including its placement, addressing, levels, mapping methods, and interaction with main memory. Key points:
- Cache memory is high-speed SRAM located on or near the CPU that stores frequently accessed data from main memory for quick access by the processor.
- Caches are organized into multiple levels (L1, L2, L3) based on access speed and size, with L1 being fastest and smallest and L3 largest and slowest.
- Cache mapping determines where main memory blocks are placed in cache and includes direct, associative, and set associative methods. Direct mapping places each block in a single cache line.
- Cache hits
This document provides an overview of memory organization and cache memory. It discusses the memory hierarchy from fast, small registers and caches closer to the CPU to larger, slower main memory and permanent storage like disks further away. Cache memory stores recently accessed data from main memory to speed up future accesses by taking advantage of temporal and spatial locality. Caches can be direct mapped, set associative, or fully associative and use different replacement policies like LRU when a block needs to be evicted.
Cache memory improves processor performance by storing copies of frequently used data from main memory closer to the processor in cache memory. There are separate instruction and data caches. When the processor needs to access data, it first checks the relevant cache - if the data is present (a cache hit) access is faster, if not (a cache miss) the data must be fetched from main memory which takes longer. Cache performance is measured by hit and miss rates, with lower miss rates improving performance. Cache entries contain the cached data as well as address tags to match cache contents with memory locations.
Cache memory is a small, high-speed memory located between the CPU and main memory. It stores copies of frequently used instructions and data from main memory in order to speed up processing. There are multiple levels of cache with L1 cache being the smallest and fastest located directly on the CPU chip. Larger cache levels like L2 and L3 are further from the CPU but can still provide faster access than main memory. The main purpose of cache is to accelerate processing speed while keeping computer costs low.
Cache memory is a small, high-speed memory located between the CPU and main memory. It stores copies of frequently used instructions and data to accelerate access times. There are three levels of cache - L1, L2, and L3 - with L1 being the smallest and fastest, located directly on the CPU chip. Cache memory utilizes the principle of locality of reference, where programs tend to reuse the same data and instructions. This allows the cache to improve performance by retaining recently accessed content.
The document discusses memory hierarchy and technologies. It describes the different levels of memory from fastest to slowest as processor registers, cache memory (levels 1 and 2), main memory, and secondary storage. The main memory technologies discussed are SRAM, DRAM, ROM, flash memory, and magnetic disks. Cache memory aims to speed up access time by exploiting locality of reference and uses mapping functions like direct mapping to determine cache locations.
Cache coherence refers to maintaining consistency between data stored in caches and the main memory in a system with multiple processors that share memory. Without cache coherence protocols, modified data in one processor's cache may not be propagated to other caches or memory. There are different levels of cache coherence - from ensuring all processors see writes instantly to allowing different ordering of reads and writes. Cache coherence aims to ensure reads see the most recent writes and that write ordering is preserved across processors. Directory-based and snooping protocols are commonly used to maintain coherence between caches in multiprocessor systems.
MODULE-4 - Memory-System used in Computer organizationMadhuraNK
The document discusses cache memories and how they improve processor performance. Cache memories store frequently accessed instructions and data from main memory in a faster cache located closer to the processor. This takes advantage of locality of reference, where programs tend to access the same memory locations repeatedly. On a cache hit, the processor can access the needed data from the fast cache instead of waiting for the slower main memory, improving performance. On a cache miss, the needed block of memory is copied from main memory to cache.
The document discusses cache memory. It begins with an introduction to cache memory, explaining that it is a small, high-speed buffer located between the CPU and main memory that holds copies of frequently used instructions and data. It then covers various topics related to cache memory such as its structure and organization, performance, coherence, mapping techniques, and synchronization mechanisms. The document contains sections on different levels of cache memory and how cache memory works.
The cache is a small amount of fast memory located close to the CPU that stores frequently accessed and nearby data from main memory in order to speed up data access times for the CPU. Without cache, every data request from the CPU would require accessing the slower main memory. Caches exploit the principle of locality of reference, where programs tend to access the same data repeatedly, to improve performance by fulfilling many requests from the faster cache instead of main memory.
Cache memory is a fast memory located between the CPU and main memory that stores frequently accessed instructions and data. It improves system performance by reducing memory access time. Cache is organized into multiple levels - L1 cache is closest to the CPU, L2 cache is next, and some CPUs have an L3 cache. (Level 1, 2, 3 caches refer to their proximity to the CPU.) Cache memory uses SRAM instead of DRAM for faster access. It is organized into rows containing a data block, tag, and flag bits. Optimization techniques for cache include improving data locality through code transformations and maintaining coherence across cache levels.
The document discusses the memory hierarchy and cache memories. It begins by describing the main components of the memory system: main memory and secondary memory. The key issues are that microprocessors are much faster than memory, and larger memories are slower. To address this, a memory hierarchy is used that combines fast, small, expensive memory levels with slower, larger, cheaper levels. Caches are discussed as a small, fast memory located between the CPU and main memory. Caches improve performance by exploiting locality of reference in programs. Different cache organizations like direct mapping and set associative mapping are described to determine where blocks are placed in the cache on a miss.
This document discusses various concepts related to computer memory. It defines key terminology like capacity, word size, and access time. It describes different types of memory technologies like RAM, ROM, SRAM and DRAM. It also discusses memory hierarchy concepts like cache organization, cache performance, and cache optimization techniques. Finally, it provides an overview of external storage technologies like RAID levels 0, 1, 5 and 10.
This document describes a cache simulator project. It discusses cache memory, types of cache including L1, L2 and L3 caches. It also describes cache mapping techniques like direct mapping, associative mapping, and set associative mapping. The document explains cache hits and misses. It covers write policies like write-back and write-through. Replacement algorithms like FIFO and LRU are also summarized. The cache simulator calculates metrics like hit rate, runtime, and memory access latency based on a memory access pattern file. It is implemented using data structures like queues for FIFO and doubly linked lists for LRU replacement.
Cache memory is a small, fast memory located close to the CPU that stores frequently accessed data from main memory to speed up processing. It is organized into multiple levels - L1 cache is inside the CPU, L2 cache is external, and main memory is L3. The cache improves performance by reducing access time - when data is in cache it is a "hit" and very fast to access, while a "miss" requires loading from main memory which is slower. Factors like cache size, mapping technique, replacement policy, and write strategy impact how efficiently it services memory requests.
This document discusses virtual memory and cache memory. It defines virtual memory as a technique that allows programs to behave as if they have contiguous memory even if the actual physical memory is fragmented. It also describes how virtual memory provides each process with its own address space and hides fragmentation. The document also defines cache memory as a small, fast memory located close to the CPU that stores frequently accessed instructions and data to improve performance. It describes levels 1 and 2 caches and how they work with memory and disk caches.
The document discusses memory hierarchy and cache performance. It states that a cache memory is a very high-speed memory used to increase processing speed by making currently used programs and data readily available to the CPU. When the CPU needs to access memory, the cache is checked first. If the data is in the cache (a hit), it can be read quickly. If not (a miss), the slower main memory must be accessed. Cache performance is measured by hit ratio. Separate instruction and data caches are commonly used to avoid bottlenecks when load/store instructions are executed.
Computer architecture refers to the operational design of a computer system. This lecture focuses on the memory subsystem aspects of computer architecture, including memory hierarchy, memory performance, cache organization and operation, random access memory technologies, and bus interfaces. Key topics discussed are memory hierarchy principles like smaller and faster memory levels, cache hit rates, direct mapped, set associative, and write-back caching techniques, and differences between static and dynamic random access memory technologies.
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Cricket management system ptoject report.pdfKamal Acharya
The aim of this project is to provide the complete information of the National and
International statistics. The information is available country wise and player wise. By
entering the data of eachmatch, we can get all type of reports instantly, which will be
useful to call back history of each player. Also the team performance in each match can
be obtained. We can get a report on number of matches, wins and lost.
Covid Management System Project Report.pdfKamal Acharya
CoVID-19 sprang up in Wuhan China in November 2019 and was declared a pandemic by the in January 2020 World Health Organization (WHO). Like the Spanish flu of 1918 that claimed millions of lives, the COVID-19 has caused the demise of thousands with China, Italy, Spain, USA and India having the highest statistics on infection and mortality rates. Regardless of existing sophisticated technologies and medical science, the spread has continued to surge high. With this COVID-19 Management System, organizations can respond virtually to the COVID-19 pandemic and protect, educate and care for citizens in the community in a quick and effective manner. This comprehensive solution not only helps in containing the virus but also proactively empowers both citizens and care providers to minimize the spread of the virus through targeted strategies and education.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Sachpazis_Consolidation Settlement Calculation Program-The Python Code and th...Dr.Costas Sachpazis
Consolidation Settlement Calculation Program-The Python Code
By Professor Dr. Costas Sachpazis, Civil Engineer & Geologist
This program calculates the consolidation settlement for a foundation based on soil layer properties and foundation data. It allows users to input multiple soil layers and foundation characteristics to determine the total settlement.
Online train ticket booking system project.pdfKamal Acharya
Rail transport is one of the important modes of transport in India. Now a days we
see that there are railways that are present for the long as well as short distance
travelling which makes the life of the people easier. When compared to other
means of transport, a railway is the cheapest means of transport. The maintenance
of the railway database also plays a major role in the smooth running of this
system. The Online Train Ticket Management System will help in reserving the
tickets of the railways to travel from a particular source to the destination.
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2. WHAT IS CACHE ?
A cache memory is a fast and relatively
small memory, that stores the most recently
used (MRU) main memory(MM) (or working
memory) data.
It is simply a copy of a small data segment
residing in the main memory.
Hold identical copies of main memory.
The function of this is to speed up the MM
data access.
3.
4. Memories that consists of circuits capable of retaining their state
as long as power is applied are known as static memory.
Less expensive RAM‟s can be implemented if simplex calls are
used such cells cannot retain their state indefinitely. Hence they
are called Dynamic RAM’s (DRAM). The information stored in a
dynamic memory cell in the form of a charge on a capacitor and
this charge can be maintained only for tens of Milliseconds.
Latency is one of the parameter indicating good performance
Latency: It refers to the amount of time it takes to transfer a word
of data to or from the memory.
5.
6.
7. Functional principles of the cache memory
In MM read operation, the cache controller first of all
checks if the data is stored in cache.
In case of match (Hit - cache hit ) the data is fastly and
directly supplied from the cache to the processor
without involving the MM.
Else (Miss - cache miss ) the data is read from MM.
A cache hit is a state in which data requested for
processing by a component or application is found in
the cache memory. It is a faster means of delivering
data to the processor, as the cache already contains
the requested data.
8. A cache hit occurs when an application or software
requests data. First, the CPU looks for the data in its
closest memory location, which is usually the primary
cache. If the requested data is found in the cache, it is
considered a cache hit.
A cache hit serves data more quickly, as the data can be
retrieved by reading the cache memory.
Cache miss is a state where the data requested for
processing by a component or application is not found in
the cache memory. It causes execution delays by
requiring the program or application to fetch the data
from other cache levels or the main memory.
9. Each cache miss slows down the overall process because
after a cache miss, the CPU will look for a higher level
cache, such as L1, L2, L3 and RAM for that data.
Further, a new entry is created and copied in cache
before it can be accessed by the processor.
The more cache hits the better.
10. Cache Memory operation is based on two
major "principles of locality"
Temporal locality
Spatial locality'
Temporal locality
Data which have been used recently have high likelihood of
being used again.
A cache stores only a subset of MM data – the most recent-used
MRU. Data read from MM are temporary stored in cache. If the
processor requires the same data, this is supplied by the cache.
11. Spatial locality
If a data is referenced, it is very likely that nearby data will be
accessed soon.
Instructions and data are transferred from MM to the cache in
fixed blocks (cache block), known as cache lines. Cache line
size is in the range of 4 to 512 bytes.
Most programs are highly sequential. Next instruction usually
comes from the next memory location. Data is usually
structured and data in these structures normally are stored in
contiguous memory locations (data strings, arrays, etc.).
Large lines size increase the spatial locality but increase also the
number of invalidated data in case of line replacement .
12. MAPPING FUNCTIONS
1. Direct mapping
The simplest way to determine cache locations in which to store
memoty blocks is the direct mapping technique.
2. Associative mapping
In this method, the main memory block can be placed into any cache
block position.
12 tag bits will identify a memory block when it is resolved in the
cache.
The tag bits of an address received from the processor are compared
to the tag bits of each block of the cache to see if the desired block is
persent.This is called associative mapping.
3. Set-associative mapping
It is the combination of direct and associative mapping. The blocks of
the cache are grouped into sets and the mapping allows a block of the
main memory to reside in any block of the specified set.
13. Block 1
Block 0
Block 127
Block 0
Block 1
Block 127
Block 128
Block 129
Block 255
Block 256
Block 257
Block 4095
tag
tag
tag
cache
Main
memory
DIRECTION MAPPING
14. Block 1
Block 0
Block 127
Block 0
Block 1
Block i
Block 257
Block 4095
tag
tag
tag
cache
Main
memory
ASSOCIATIVE MAPPING
15. Block 1
Block 0
Block 126
Block 0
Block 1
Block 63
Block 64
Block 65
Block 127
Block 128
Block 129
Block 4095
tag
tag
tag
cache
Main
memory
Block 2
Block 3
tag
tag
Block 127tag
Set 0
Set 1
Set 63
SET-ASSOCIATIVE MAPPING
16. The Cache memory stores a reasonable number of blocks at a given
time but this number is small compared to the total number of blocks
available in Main Memory.
The correspondence between main memory block and the block in
cache memory is specified by a mapping function.
The Cache control hardware decide that which block should be
removed to create space for the new block that contains the
referenced word. The collection of rule for making this decision is
called the replacement algorithm.
The cache control circuit determines whether the requested word
currently exists in the cache. If it exists, then Read/Write operation
will take place on appropriate cache location.
In this case Read/Write hit will occur.
17. REPLACEMENT POLICIES
1. First In First Out (FIFO)
Using this algorithm the cache behaves in the same way as a FIFO
queue. The cache evicts the first block accessed first without any regard
to how often or how many times it was accessed before.
2. Last In First Out (LIFO)
Using this algorithm the cache behaves in the exact opposite way as a
FIFO queue. The cache evicts the block accessed most recently first
without any regard to how often or how many times it was accessed
before.
3. Least Recently Used (LRU)
Discards the least recently used items first. This algorithm requires
keeping track of what was used when, which is expensive if one wants
to make sure the algorithm always discards the least recently used item.
General implementations of this technique require keeping "age bits" for
cache-lines and track the "Least Recently Used" cache-line based on
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