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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Can one core on a multicore linux system be dedicated to one user-space app?

Can a core be dedicated to one user-space app (e.g. for the purpose of bit-banging GPIO without any interruptions)?
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/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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26 views

Why is 'steal' time gradually increasing?

I'm tracking CPU usage on a VM on a lightly-loaded host. Everything appears to be functioning normally on all the VMs, but collectd is reporting a gradually increasing 'steal' time: The actual ...
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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 ...
69
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3answers
39k views

What do the flags in /proc/cpuinfo mean?

How can I tell whether my processor has a particular feature? (64-bit instruction set, hardware-assisted virtualization, cryptographic accelerators, etc.) I know that the file /proc/cpuinfo contains ...
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7answers
14k views

Getting cpu usage same every time.

When I execute following command to get cpu usage , I get nice + user cpu usage. top -b -n1 | grep "Cpu(s)" | awk '{print $2 + $4}' Output: 14.5 Here I am getting problem is that the output ...
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1answer
716 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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38 views

How to reduce temperature of my Toshiba with Slackware?

I have a Notebook Toshiba with Slackware 14.1 64bits $ lspci: 00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 ...
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In Linux “top” command what are us, sy, ni, id, wa, hi, si and st (for CPU usage)?

When I issue $ top in linux, I get a result similar to this (see here). One of the lines has CPU usage information represented like this: Cpu(s): 87.3%us, 1.2%sy, 0.0%ni, 27.6%id, 0.0%wa, ...
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24 views

Isolating some CPU cores reduce average CPU usage of game servers

Hardware: FX8320 (8 cores) @ 4.4GHz, 16GB I run 10 TF2 game servers. Few days ago I isolated some CPU cores with line in linux grub config: isolcpus=5-7 The strange thing - individual CPU cores ...
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1answer
26 views

How to check whether my AIX is PPC OR PPC64?

My AIX machine is currently running on 6.1 OS. I would like to know whether it is on PPC OR PPC64, Is there any command other than arch which gives the information about PPC ?
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Does cpulimit stop a process?

One terminal runs: $ pdfcrack -o -q my.pdf The second terminal then runs: $ cpulimit -e pdfcrack -l 30 Process 7826 detected On the first terminal, there is output: $ pdfcrack -o -q my.pdf ...
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2answers
70 views

Are “kernel mode” and “user mode” hardware features or software features?

I read that there are two modes called “kernel mode” and “user mode” to handle execution of processes. (Understanding the Linux Kernel, 3rd Edition.) Is that a hardware switch (kernel/user) that is ...
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4answers
3k views

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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1answer
101 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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41 views

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
229 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
194 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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4answers
150 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 ...
2
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2answers
49 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
7k views

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
450 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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2answers
3k views

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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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
80 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 ...
2
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1answer
107 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
20 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 ...
8
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2answers
450 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 ...
1
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1answer
62 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 ...
9
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3answers
9k views

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
40 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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26 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
38 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
41 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
63 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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0answers
84 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 ...
3
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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 ...
0
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1answer
26 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 ...
0
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1answer
196 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
51 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 ...
0
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2answers
47 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. ...
5
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1answer
144 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 ...
0
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1answer
53 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
91 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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66 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
151 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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52 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 ...
3
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2answers
59 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, ...