The CPU (Central Processing Unit), is the chip in the computer that actually performs the operations and calculations that are done as a program runs. It is essentially what executes a program.

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Understanding top and load average

I'm observing a high load average on a certain machine (about 9) in all three load fields. I understand load as the number of processes in state "run" / currently desiring CPU time. Am I correct at ...
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70 views

AIX CPU usage - how to know how many CPUs running?

Over AIX 6.1 - I do see the following output, it says I have 16 Max Physical CPUs; but there are only 8 active - why is that? The system will use the remaining 8 if needed? Or are they disabled? # ...
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CPU always at 80°C while the system is idle

My system is quite unused at the moment: %Cpu(s): 10.3 us, 3.1 sy, 0.0 ni, 85.9 id, 0.7 wa, 0.0 hi, 0.0 si, 0.0 s but still the temps sensors give me are quite high: acpitz-virtual-0 ...
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2answers
146 views

Kondemand process consumes most of my CPU

Following is the output from top: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 3551 mysql 20 0 10.0g 84m 4052 S 9.4 0.1 544:39.87 mysqld 2311 root 20 0 0 ...
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1answer
160 views

CPU speed and cat /proc/cpuinfo

I use centos 6.4 64. I have old proc - CPU AMD Phenom II X4 810 (HDX810W) 2.6 GHz. However, when I execute the command cat /proc/cpuinfo I get the following: processor : 0 vendor_id : ...
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1answer
1k views

/proc/cpuinfo showing zero cpu clock speed

I saw an interesting issue where the cpuinfo file from /proc filesystem shows the cpu clock speed as zero. It is a physical host with no virtualization. Can someone explain to me some probable reasons ...
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4answers
127 views

Run linux process at very very low priority?

I have regular process that not so important but will consume so much CPU power, and I have another process which is really important, but it spend most of the time idle, but when it got a job it ...
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1answer
683 views

Linux Mint CPU cores balancing and high temprature

I'm using Linux Mint. My laptop has a Corei5 CPU. When I check the system monitor, it shows that the CPU 1 usage is between 90 to 100% and CPU 2,3,4 are less than 5%. why it doesn't balance processes ...
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2answers
42 views

Pipe Viewer - Progress monitor performance consequence

I am writing a batch script to sort through gigs and gigs of data. All of the data is text but the script will take a long long time to execute. I would like to give some visual indication that the ...
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5answers
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Limiting processes to not exceed more than 10% of CPU usage

I operate a Linux system which has a lot of users but sometimes an abuse occurs; where a user might run a single process that uses up more than 80% of the CPU/Memory. So is there a way to prevent ...
3
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1answer
437 views

cpufreqd does not control temperature plus shows no output

Since my laptop (an Acer Aspire 5750G running a Gentoo Linux with a not-quite-up-to-date kernel 2.6.39-r3 (a weird wLan hardware makes the update difficult)) tends to run rather hot I am trying to ...
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diabling cpu cores on quad core processor on linux

I want to disable 3 CPU cores and run my processor on a single core. I have used command:maxcpus=1. But after this I executed this command ls /sys/devices/system/cpu. It still shows ...
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1answer
1k views

Intel Turbo Boost apparently activated for no reason?

The other day, I reinstalled my operating system (Crunchbang, fork of Debian). For some reason my fan has been running at full speed (and blowing colder-than-room-temperature air) even though I'm ...
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2answers
4k views

How to check the cpu temperatures core by core?

I have a Phenom X3-8450e which has a total of 3 cores. But when I ran "sensors" on a terminal I got this: $ sensors atk0110-acpi-0 Adapter: ACPI interface Vcore Voltage: +0.99 V (min = ...
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2answers
65 views

top -bn1 not giving correct CPU usage

I am logging on to a node which I know has near 100% cpu usage (20 single process jobs using nearly 100% cpu each). When I use top interactively, the first iteration, it gives me about 20% ni and the ...
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1answer
93 views

Unexpected processor/core counts for AMD processor

I wanted to determine if a machine has hyperthreading enabled or not. To determine this, I used advice I found online, which operates as follows: physical_proc_count = `grep "physical id" ...
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1answer
9 views

Distributing CPU cores between cgroups and outside world

Is it possible to manage access to CPU cores in a similar fashion that memory limiting works? In particular I need to be able to dynamically create and destroy cgroups that will limit a particular ...
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2answers
354 views

Does QEMU/KVM use Intel AES instructions for encrypted qcow2 images if the host CPU has them?

The qcow2 image file format for KVM can use AES encryption. The encryption is applied at the cluster level: Each sector within each cluster is independently encrypted using AES Cipher Block ...
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1answer
59 views

What does the term 'Unix Processor' mean?

I have Googled around and found a few references to this term, but nothing which defines what it actually means. Does anyone here have experience with such a device? What features must a processor ...
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3answers
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How can I know which IRQ is responsible of high CPU usage

I've moved a server from one mainboard to another due a disk controller failure. Since then I've noticed that constantly a 25% of one of the cores goes always to IRQ however I haven't managed myself ...
2
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1answer
34 views

How to get all CPU cache information without SU access

I am trying to find out the cache mapping scheme for all the levels of class of a linux server, however I do not have root access. I would just use DMIdecode for this but you need root access. Is ...
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0answers
19 views

cpulimit on a bash script which runs other commands

I have a bash script which runs other cpu-intensive commands . When I apply cpulimit on the bash script, the output of top shows processes for the commands inside the script still run without ...
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1answer
23 views

NAS: 100% system (kernel) cpu usage

I have a single core NAS My Live Duo. It runs Debian lenny release. I found via htop utility that it constantly use 100% of red cpu without any noticeable process to eat it. Than I checked via iostat ...
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1answer
32 views

Plot values returned by command output

I have a little script that prints the CPU temperature after each T period of time, so the output is something like this: 19/02/15,01:00 30 19/02/15,02:00 33 19/02/15,03:00 38 19/02/15,04:00 32 ...
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3answers
54 views

Which commands or operations can be used to put the cpu under intense load?

I would like to measure latencies during high cpu usage but I don't have benchmarking tools like stress and I can't install them. Which operations do you recommend to put the cpu under intense load? ...
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45 views

Is it safe to disable Frequency Scaling and CPU idle Power Management support for Real Time purposes?

I'm using a Raspberry Pi board and I would like to build a real time system. During the kernel configuration, I found the CONFIG_CPU_FREQ option, which (from the help section) allows you to change ...
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4answers
1k views

Invoking CPU Stress

Looking for an app or tool to invoke CPU usage on my virtual Linux and Unix guests. I found the app "stress" from a post on Stackoverflow, but curious what the Unix/Linux crowd would recommend.
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1answer
38 views

Identify machine configuration via code

I am writing a program where I need to know about the machine configuration. Code will run on Linux. I want to find the following: Number of CPU Cores Number of CPU Sockets Number of Disks If it's ...
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1answer
24 views

Solaris prstat - definition of “recent” time used in percentages

The man page for prstat (on Solaris 10 in my case) notes that that CPU % output is the "percentage of recent CPU time". I am trying to understand in more depth what "recent" means in this context - is ...
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1answer
93 views

Should I install the AMD/Intel microcode packages when running Debian?

Should I install the AMD/Intel microcode packages when running Debian? What exactly do they do, and when should/shouldn't I install them? Why are they in non-free?
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3answers
4k views

How do I know which processors are physical cores?

I've got an Intel i7 2700k here, and I'd like to know how I can tell which processors are physical and which are virtual (ie: hyperthreading). I'm currently running a Conky script to display my CPU ...
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1answer
48 views

Is there a way to change the number of processors a program sees?

Is there any way I can trick a program into thinking the system has fewer processors? To explain: I am debugging a program that creates as many threads as it has processors, using ...
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2answers
42 views

How can I find figure out why a machine has consistently 70%+ CPU usage?

My machine (Macbookpro, Archlinux) has consistently a CPU at 70%+, yet I have no clue why. This doesn't happen on MacOS, only on Linux. Using htop, I can see no program using more than 2% of CPU. ...
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1answer
138 views

Whats the history behind the fork bomb?

I have read other question about its work and other things that Fork bombs operate both by consuming CPU time in the process of forking, and by saturating the operating system's process table. A ...
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1answer
50 views

linux + top command

I run the top command on my linux machine and I see that vim command take like 99.5% CPU PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND ...
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1answer
65 views

How can I find the CPU resource utilization of a process and all its children [duplicate]

If I have a process that spawns child processes, is there a good way to get a single number representing the combined CPU use of that process and its children? i.e is there a simple shell command ...
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1answer
59 views

How much RAM and CPU for a NTP server? [closed]

As a side project, I am thinking about adding a NTP server to pool.ntp.org. I would like to use CentOS basic, but how much RAM and CPU should I assign to a machine that will only be running ntpd (plus ...
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1answer
133 views

Why does a linux guest consume 100% of the host CPU under VirtualBox when the guest appears idle?

I am using VirtualBox on a Macbook Pro running Yosemite. My linux guests sometimes consume 100% of the host CPU (viewed in Activity Monitor) even though the guest is idle. Why is the host CPU ...
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47 views

/proc/stat - is guest counted into user time?

I have a quick question. In man page for /proc/stat this is not clear to me: Is guest and guest_nice time included in user time in /proc/stat? http://man7.org/linux/man-pages/man5/proc.5.html in ...
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2answers
53 views

Test if valid executable

Is there a (relatively) simple way to test if an executable not only exists, but is valid? By valid, I mean that an x86_64 Mach-O (OS X) executable will not run on an ARM Raspberry Pi. However, ...
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13 views

cacti Cannot display pictures

I install the nagios+cacti in the centos6.4, but the CPU picture drawing, others such as memory, processes are normal. This is why?
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0answers
34 views

arch linux on alienware 14

I've tried to install arch in my New alienware 14 But i got a few errors there, squashfs is making trouble and something is stuck in the CPUs. Does someone have experiences with that?
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37 views

What does the “k” metric mean in the “sa” output?

From man sa: k cpu-time averaged core usage, in 1k units My questions: How is it calculated? What is the significance?
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1answer
95 views

High %sy in top output, how to debug?

We have 2 identically configured servers and one of them is showing a high %sy while the other does not. This would seem to indicate that the system is busy doing something. Cpu(s): 28.1%us, ...
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0answers
128 views

Get CPU time for Benchmark in Bash Script

I'm using this Method here: http://giantdorks.org/alain/how-to-benchmark-individual-shell-script-sections-to-identify-slow-parts/ to Benchmark my Bashscript: RuntimePrint() { duration=$(echo ...
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3answers
937 views

How to enable safeguards for CPU temperature

My desktop has a nasty habit. When I have several high intensity applications running and my CPU is at maximum usage for a period of time, the core temperature rises and my computer auto-shuts off. ...
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1answer
167 views

Why PowerVM LPAR CPU utilization is negative

For a specific case I compute an PowerVM LPAR CPU utilization to be a large number less than zero. I am fetching the lpar sample event using: lslparutil -r lpar -m P750 --filter "lpar_names=i5lp5" ...
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219 views

System CPU Time and User CPU Time Calculation for a Process in Linux

I want to calculate CPU time consumption of a particular process in system mode and user mode using statistics present in /proc/<PID>. There are two fields utime and stime in ...
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1answer
69 views

Does it take time for process to utilize CPU?

I have a single-core x86 machine where I execute the burnP6(from cpuburn package) for 1 second and then kill the program: while true; do /usr/bin/burnP6 & sleep 1; pkill burnP6; sleep 1; done ...
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1answer
554 views

Where is PCB on linux

A PCB is a process control block , this is its definition on Wikipedia Process Control Block (PCB, also called Task Controlling Block,[1] Task Struct, or Switchframe) is a data structure in ...