Questions tagged [cpu-cache]

High speed RAM which is used by the computer processor to store often-used operations for the purpose of taking less time to perform large computational tasks

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Can anyone make sense of some simple hardware counter results from perf

I want to use perf to analyze some performance problems with a large program. To make sure I understand the various perf results I'm testing perf with some simple known workloads. I started out ...
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Can one core perform several operations/instructions during one tick (because core has different execution units)?

A core has its own execution units and load/store buffers (additional "cache" - in addition to L1). Do those execution units have their own registers? Do cores also have their own dedicated registers?...
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Choosing optimal server specs for MCMC computation

My research group is investing in a server to analyze human movement patterns using large amounts of cell phone usage data. We want a machine that is optimized for MCMC algorithms because we fit large ...
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How a program is executed on a CPU with 3 level of caches? [closed]

We have a system optimization problem that requires a clear workflow of the execution of a CPU. How does a modern CPU (e.g. Intel Xeon) with multiple levels of caches execute a program originally ...
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How is the micro-op cache tagged?

According to Real World Technologies’ article on “Intel’s Sandy Bridge Microarchitecture”: “Sandy Bridge’s uop cache is organized into 32 sets and 8 ways, with 6 uops per line, for a total of 1.5K ...
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How to know the cache replacement policy of my computer's cpu

How to know the cache replacement policy of my computer's cpu?LRU or FIFO or Random? this is my laptop's processor:Intel(R) Core(TM) i3-4030U CPU @ 1.90GHz. Is there having some command to know that?
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Do process switch between different cores?

Will a process switch between different cores to increase performance? If the process does jump between cores, which components are shared across cores? L1-L3 cache, registers or memory?
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“Missing” L3 Cache in Opteron 6274 on Windows Server

I have 4x AMD Opteron 6274 CPUs in an HP DL585 G7 server. Windows Server 2016 only shows these CPUs as having 12MB ea. of L3 cache, although every source on the internet says they should have 16MB (...
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From which memory do CPUs actually read data?

In accordance with my own understanding, for data to be processed by CPU, it should be placed in RAM, in the meantime CPUs themselves have cache memory, that is also used to access data. It's a pretty ...
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Direct-mapped cache: how to determine address decomposition

Let's assume I have a 32 bits addressable memory and a 4 kib direct-mapped cache. Let's say that every entry (line) of the cache is composed of a unique word (32 bits). We can infer that the index's ...
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261 views

Memory Caches - Sizes of individual levels

I was just wondering when a program such as CPU-Z or CPU-ID detects your cache levels and it says, for example: L1 D-Cache Size: 16Kb "x 8" (4 way set associative) L1 I-Cache Size: 64 Kb "x 4" (2-way ...
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What does L4 cache hold on some CPUs?

All modern multi-core CPUs have at least a three-level cache (refer to Why do we need multiple levels of cache memory?). L1 is the fastest and smallest, L2 has slightly more latency but is larger, ...
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What software can write to Cache memory?

I was working through a Higher Computing past paper and the following question came up Describe a situation where the cache memory would not improve the processor’s performance (1 mark) The ...
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How to force MS word to “cache” a large doc —while opening? (And not after beginning working on it)

I am working with large documents which (probably) requires word to "cache" large amount of data. So it freezes, (high CPU, fan) during few minutes, after few minutes of editing. The freezing probably ...
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Is it possible to run Windows 98 SE from L3 cache with no RAM installed?

Modern CPUs can have L3 cache in the range of tens of megabytes (e.g. 24MB). W98SE requires at least 16MB of RAM to run (24MB recommended). Is it possible to use the L3 cache as RAM, without any ...
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which one of these units is not located in the microprocessor?

I'm doing a test on general computer science and I think the answer sheet is wrong. The question is as follows: which one of these units is not located in the microprocessor? 1) Cache memory ...
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Is ARM PL310 only in Cortex A9 processor?

I know that ARM Cortex A9 processor can be equipped with PL310 cache controller. However, I'm not sure if other ARM processors may support PL310 cache controller? I searched Cortex A7, A53, and A57, ...
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L3 data cache ECC error

I happened to have a terminal window open in Linux (Debian) and, as I was browsing the web, I heard a beep so I looked to see what happened and I found the following message in the terminal window: ...
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How many bits are in the address field for a directly mapped cache?

Here is the problem I am working on: 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 ...
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710 views

My L3 cache size showing zero in wmic (cmd)

I purchased a desktop system which has 6 MB Cache. When I checked the L3 cache in the BIOS I didn't find a L3 cache. I the tried to use another method in from the command line to confirm the L3 cache ...
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How is addressing done of L1/L2/L3 cpu caches vs. ram allocation? [closed]

As cache sizes on cpus increase, how is it managed vs. RAM? Do considerations need to be made while making an application to ensure you're getting the most out of your Cache or is that completely at ...
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When is CPU cache flushed back to main memory?

If I have a CPU with two cores, each core has it's own L1 cache, is it possible that Core1 and Core2 caches a same part of memory at the same time? If it is possible, what the value of the main memory ...
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Missing L1 cache characteristic

I wrote simple program (with help of Igor Ostrovsky's article 'Gallery of Processor Cache Effects') which supposed to examine levels of cache in my processor. According to Coreinfo provided by ...
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Is too big cache a bad idea? [duplicate]

I am going to pack a new computer for myself and I thought about Xeon series as main processor. Xeons tend to have very big caches even up to 32MB. And here is a question: Is it a big advantage to ...
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In L1, L2 cache and DRAM, is sequential access faster than random access?

In L1, L2 cache and DRAM, is sequential access faster than random access because of the possibility to establish read-ahead? I know in HDDs this is of-course faster in orders of magnitude.
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Why is loading chunks of data into the cpu cache an efficient way of processing?

I know that loading instructions into the cache increases the speed of processing overall. Is the answer to the question connected to organization and speed?
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Syslogd: hardware error

The machine has been sending these messages to the terminal, paired with beeps from the speaker on the motherboard. These messages appear every 5 minutes, sometimes naming CPU2, sometimes CPU3. ...
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Processors cache L1, L2 and L3 are all made of SRAM?

Are Processor caches L1, L2 and L3 all made of SRAM? If true, why L1 is faster than L2 and L2 is faster than L3? I did not understand this part when I read about them.
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Tradeoff: CPU Clock Speed vs Cache [closed]

If you had two choices in processors, one with 2.7GHz @ 6M cache, and the other with 3.0GHz @ 4M cache, which do you choose? This is not a shopping question, what I'm looking for is a general rule ...
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Is CPU cache (L1 - Ln) equal to TLB

If we are talking about CPU cache. Is Ln synonym for saying 'TLB (translation lookaside buffer) of type Ln' or does Ln include also somethin else than just TLB?
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Why do we need multiple levels of cache memory?

In general a cache memory is useful because the speed of the processor is higher than the speed of the ram (they are both increasing in speed but the difference still remains). So reducing the number ...
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Too much RAM “in cache”

I am having the following problem: I am having a completely new Notebook with 8 GB RAM and Windows 8. I do not use software that requires a lot of RAM and I do not have a thousand programs running. ...
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Why is SRAM faster than DRAM?

In modern multi-core processors, the processor caches (L1,L2 and L3) are made up of SRAM with decreasing speeds(L2 caches are higher speed SRAM than L3 caches which is a cost trade-off). The main ...
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Back of the envelope calculation for speed of matrix multiplications [closed]

I'm trying to develop an intuition for how feasible/scalable machine learning algorithms are. The dominant cost is always matrix multiplications, but there seem to be no readily Google-able resource ...
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Is it a big downside for a cpu to not report the L1 Cache?

I am reading information for a processorAMD FX-8320 Eight-Core My primary question is why the L1 cache is not in the information. Would this imply that it does not have registers that it can access ...
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How can I get to know CPU cache size on Windows 7

WMIC CPU command displays a lot of information about the CPUs on a machine. It only displays the information about L3 cache, is there a way to figure out the size of L1 and L2 caches using a command ...
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L2 and L3 Cache Difference?

While I understand that the computer cache is: A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster ...
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meaning of files in cpu folder of linux

What's the meaning of files in the folder /sys/devices/system/cpu/cpu0/cache/index0? I see these files in the folder: coherency_line_size number_of_sets shared_cpu_list size ...
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how to make caches with equal bitline and wordline lengths?

We know to minimize delay of cache structures in microprocessors, the bitline wire length and wordline wire length should be relatively the same. So in other words, cache modules in processors should ...
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shared L2 in multicore: regarding miss per kilo instruction (MPKI) counting

I am using multicore simulator marss http://marss86.org. I am using 4-core simulation, with shared L2 cache. Each core is run for say, 100M instructions. Since different cores progress at different ...
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CPU L3 cache miss and hit ratio details

I am on a Linux server with Xeon X7560 CPU. How can I see the CPU L3 cache miss and hit ratio details?
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Is the cache size or number of cores more important when weighing CPU performance?

I'm shopping for a laptop for my son to use for school, so it doesn't need to be a gaming machine. I've put together PC's from scratch before, but it's been a while. I've noticed that a number of ...
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What is a processor cache?

I recently downloaded CPU-Z just to check things out, and saw a tab marked Cache on it. It shows what appears to be different memory sizes, and I have seen processors being advertised with an X sized ...
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Size of L1 cache

Typically, how big is L1 cache today?
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Is Cache memory located in the CPU or at the motherboard?

I have a doubt whether cache memory is located in the processor or at the motherboard?
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L2 Vs. L3 CPU cache speed and performance

In the past few years, looking at Intel CPUs, there has been a move from large size L2 cache to large size L3 cache. A lot of this is due to having more cores on the CPU and wanting to share the cache ...
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Which property of CPUs is good for what?

Back in the days clock frequency used to be THE criteria to compare CPUs (or perhaps you had to take into account whether it was a DX or SX). The world was simple back then, but in these fast evolving ...
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Where exactly L1, L2 and L3 Caches located in computer?

Where exactly L1, L2 and L3 Caches Located in computer ? I know, we use Cache to increase performance by picking DATA and INSTRUCTIONS from Cache rather than Main Memory. Following are my questions ...
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Running programs in cache and registers

In my operating systems class we were shown a picture depicting a hierarchy of memory starting from most expensive and fastest at the top and least expensive and slowest at the bottom. At the very top ...
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RAM size > L2 Cache size > L1 Cache size > Internal Registers of a CPU

I understand that the access speed of internal registers is very high compared to that of L1 Cache and L1 Cache can be accessed faster than that of L2 cache which in turn can be accessed faster than ...