Questions tagged [cpu-cache]

A fast memory limited in space close to the CPU. A cache is designed to reduce the average time to access memory.

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6
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1answer
19k views

Tag, index and offset of associative cache

My main issue of a homework problem is trying to figure out the different parts of the chart. I have a 3 way set associative cache with 2 word blocks, total size of 24 words. I am given $3, 180, 43, 2,...
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0answers
2k views

Will this address result in a cache hit or miss for these cache mapping functions?

The Problem: A CPU produces the following sequence of read addresses in hex.    Suppose the cache is empty to begin with and assuming an LRU replacement, determine whether each address ...
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0answers
86 views

Is this cache entry a hit or a miss? [duplicate]

The Problem: A CPU produces the following sequence of read addresses in hex. Suppose the cache is empty to begin with and assuming an LRU replacement, determine whether each address produces a hit or ...
61
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2answers
26k views

What happens to the cache contents on a context switch?

In a multicore processor, what happens to the contents of a core's cache (say L1) when a context switch occurs on that cache? Is the behaviour dependent on the architecture or is it a general ...
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5answers
282k views

How to calculate the number of tag, index and offset bits of different caches?

Specifically: 1) A direct-mapped cache with 4096 blocks/lines in which each block has 8 32-bit words. How many bits are needed for the tag and index fields, assuming a 32-bit address? 2) Same ...
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1answer
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How does a TLB and data cache work?

I'm trying to study for an exam and I realized I'm confused about how the TLB and data cache work. I understand that the TLB is essentially a cache of most recently used physical addresses. However, ...
38
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2answers
2k views

Are generational garbage collectors inherently cache-friendly?

A typical generational garbage collector keeps recently allocated data in a separate memory region. In typical programs, a lot of data is short-lived, so collecting young garbage (a minor GC cycle) ...
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1answer
2k views

Understanding the basic concepts in memory organisation

(Before actually proceeding to the question, I want to confess that this is a homework question, please do consider it and help me in improving my understanding a bit more.) I have recently started ...
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1answer
2k views

Why is quiescent consistency compositional, but sequential consistency is not

I'm having trouble in comparing these two memory consistency models. Essentially for sequential consistency I think of real code like this: ...
9
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2answers
50k views

Cache Direct Map (Index, tag, hit/miss)

Alright, I thought I understood this concept but now I am confused. I looked up similar problems and their solutions to practice, and that's what threw me off. The question is a homework problem which ...
14
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1answer
380 views

Research on evaluating the performance of cache-obliviousness in practice

Cache-oblivious algorithms and data structures are a rather new thing, introduced by Frigo et al. in Cache-oblivious algorithms, 1999. Prokop's thesis from the same year introduces the early ideas as ...
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2answers
16k views

Cache effective access time calculation

In order to calculate the effective access time of a memory sub-system, I see some different approaches, a.k.a formulas. All are reasonable, but I don't know how they differ and what is the correct ...
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1answer
10k views

Hit/Miss in a 2-way set associative cache with offset

"In a 2-way set associative cache of 4 blocks containing 4 words each, which one of these addresses will return a hit when being read? The blocks to be retained in the cache are decided by LRU." 4 ...
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2answers
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Understanding Multilevel Caches

I'm reading multi-level cache and came across a question through which i got confused. I've read that Between processor and Cache Word/ Byte is transfered Between Cache and Main memory Block(...
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1answer
422 views

Loading a word from a byte addressed cache

In a cache with byte addressing, the byte you want to load is selected using the block offset. But what if I execute a LW instruction and don't want a single byte but a full 32 bit word? Is there ...
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4answers
181 views

Compiler instructions to sync core caches: are they really needed?

I have read reviews of this book, and quote the following from one of the reviews (emphasis mine): Other than straining your eyes with old-styled C++, you can read such misconceptions in the book ...
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1answer
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How many bits would be needed for the byte?

The Problem: A high speed workstation has 64 bit words and 64 bit addresses with address resolution at the byte level. Assuming a direct mapped cache with 8192 64 byte lines, how many bits are in ...