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Questions tagged [cpu]

The central processing unit or "processor" inside a computer which executes the instructions in a computer program.

The central processing unit (CPU) is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. The central processing unit carries out each instruction of the program in sequence, to perform the basic arithmetical, logical, and input/output operations of the system. This term has been in use in the computer industry at least since the early 1960s. The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation remains much the same.

Source: Wikipedia

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Limit to N cores, but I don't know which ones

With taskset, I can limit a process to run on a specific CPU. I am submitting jobs through a load scheduling facility on a high performance cluster, and consequentially, when I submit the jobs I don't know: on what node they will run how many cores…
gerrit
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CPU simulator with an assembler, linker with Simple assembly

Do somebody know some CPU simulator featuring simple assembly language with assembler, loader, linker for learning and testing purpose. That I could run on GNU systems.
Sharad
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Why is there a time gap bigger than a cycle when measuring a cycle with perf?

I used the command perf record -a to measure the performance counters on my system and perf script to obtain the results, which look like this [000] 109528.087598: 1 cycles [000] 109528.100038: 5072 cycles [000] 109528.120034: …
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Is perfmon in jemter analysing cpu utilisation of local machine or the server where application is hosted?

Just need to know that perfmon plugin which is used in jmeter tool, does it analyse cpu/memory, disk utilization of local machine or the server where application is hosted? Because as a user when give IP and port, we give these details of the remote…
puneetverma0711
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data bus and addressing memory confusion

I have learned 8086 CPU has 16bit data bus, and Pentium CPU has 32bit data bus, which mean each memory address holds size of data bus. For example: 16bit = 2^16 = 65,536 binary 0000 0000 0000 0000 ~ 1111 1111 1111 1111 hex 0000 0000 ~ FFFF…
Jeungwoo Park
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How can I get application its own pid. How to get cpu usage by application in Java without external libraries?

For example in linux htop: http://scr.hu/1det/r1ghl and when I check in my application cpu usage by pid: 27914 it should print me 51%. How to this do? public static int calcCPU(long cpuStartTime, long elapsedStartTime, int cpuCount) { long…
Larry
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During an x86 software interrupt, when exactly is a context switch made?

I am asking this because I am trying to implement interrupts in my toy kernel. So, I know that when an interrupt occurs, the CPU pushes various bits of information onto the stack. However, everywhere I search online shows different information in…
Michael Morrow
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When does the CPU get interrupted by interrupt or exception during pipelining?

Given a pipelined CPU, when and how does the CPU get interrupted by an interrupt or exception when executing instructions in a pipeline? In what phase is the interrupt/exception handled, and what happens to the current pipeline and/or instruction on…
Jakub Arnold
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Any tool allows to measure all cache levels in C program?

I want to study the effects of L2 cache misses on CPU power consumption. To measure this, I have to create a benchmarks that gradually increase the working set size such that core activity (micro-operations executed per cycle) and L2 activity (L2…
Kroka
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How to disable bmi instructions with GCC 4.4.7-17

I have a problem with gcc 4.4.7-17. I compiled a program in a server and ran this program in another server, but it crashed because of illegal instruction. I doubt that the difference between the two servers may cause this exception.Yes, I find…
Eric Lee
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How to store array to fit cache line size

I want to have an array with 32 elements of 64bit numbers like this : long int arr[32]; however my cache line size is 64 bytes. Does it mean my array will not go at all into the cache system or rather some of elements will do? Would it help to fit…
Tunga
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Too many rcuob and rcuos are shown

On my Linux server, Too many rcuob and rcuos process are shown. Execute a following command. ps auxwwf | grep rcu And shown below. root 9 0.0 0.0 0 0 ? S 5月30 0:00 \_ [rcuob/0] root 10 0.0 0.0 0 …
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Spark multinode is not so fast executing a query comparing to single-node, How to increase the number of cores in virtual box?

Im doing some tests with spark in virtualbox. I have a cpu with 8 cores in the host machine. And I would like to test spark with maximum cores possible in the virtualbox environment to have the best perforamnce possible. Im using 3 virtual boxs…
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PHP get CPU usage per core on a linux server

Ive seen quite a few php scripts to get and display the CPU usage as a % for all cores combined. But so far i have not been able to find a per core way of doing this. Would it be possible to create a script that would be able to get CPU usage for…
09stephenb
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Is there a execution time lower limit for Java?

I designed a program aiming to measure time consumption while avoid System.currentTimeMillis() threshold for tiny execution(may take less than 1 milli)(it will inevitably produce acceptable inaccuracy for extra operations), but the count turns out…
Eureka Zheng
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