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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FreeBSD throttle cpu clock on high temperature

I'm using a laptop with bad cooling system, so my CPU sometimes hits very high temperature, and linux kernel is able to throttle cpu clock to cool it as I can see in dmesg: [22612.245243] CPU3: Core ...
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252 views

Kernel - Measuring the rate of timer interrupts

I am working on optimizing kernels of my boxes for telephony, which involves (among other things) adjusting the HZ rate and the preemption model. Initially the kernel was compiled with the default ...
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401 views

Strange cpu usage values reported by pidstat

I have a script that reports the cpu usage of a specific program reading values from pidstat. The script launches as: pidstat -C ^frontend$ -h -l -p ALL 1 1 The values reported this way sometimes ...
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1k views

Difference between 'sar' and 'iostat' commands

With sar and iowait, we can get CPU time utilization. But, when I executed both commands, I could see significant differences in their outputs. > iostat && sar 1 1 Linux ...
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129 views

Figuring out physical cache layout in FreeBSD

I'm trying to figure out they physical cache layout of my CPU in FreeBSD 10. I see the following from sysctl kern.sched.topology_spec kern.sched.topology_spec: <groups> <group level="1" ...
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304 views

Exynos 5 DVFS or turning off cores in Ubuntu - Scaling frequency for one of the cores only (dual core) (cpufreq)

I was wondering if there is possible to scale only one of the cpu cores in the A15 in Exynos 5 ? I have tried using e.g cpufreq-set -c 1 -f 500MHz, but both cores are set to the same frequency. When ...
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327 views

eldoc mode makes emacs use 100% cpu

When I use eldoc, I add this to .emacs: (add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode) (add-hook 'lisp-interaction-mode-hook 'turn-on-eldoc-mode) (add-hook 'ielm-mode-hook ...
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32 views

Suspend system instead of shutdown on CPU overheat

I have Linux Mint. The system Linux Mint is installed on, shuts down immediately on overheating. Is there anyway the system doesn't shutdown, but goes to standby state? The machine can always be ...
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28 views

Assign virtual core number to specific real core

Is there any way to assign ''linux core numbers'' to specific real cores? I'm working with an asymmetric architecture, so not all cores are the same, and I want to assign specific cores number to ...
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318 views

CPU Pipe Underrun Errors

Every time upon booting and then unlocking my GUI session on Kali Linux 2.0, I get another of this error in Virtual Console 1: [ 1235.586792] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] ...
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55 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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643 views

Disable CPU scaling with U 1404

I know there are a lot of things about this topic but I couldn't find anything not older than 4 years. As the stuff develops so fast I hope it is fine to ask again a few years later. What is ...
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281 views

VPS freezes every few days (rcu_sched_state detected stall on CPU x)

Background: I have an Ubuntu 12.04 (64bit) in Xen virtualization environment. 1 GB RAM, 1 processor. Every few days I get the following error message: rcu_sched_state detected stall on cpu 0 ...
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155 views

Limit CPU cycles inside of Xen

I'd like to run some minimum-expectation benchmarks on EC2, but I'm having an issue of high variability in my output data. Specifically, they keep giving me more CPU than I'm minimally entitled to, ...
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269 views

Unable to reduce core frequency freebsd

I'm working on a FreeBSD project where I need to maintain the temperature of the processor below a threshold value. In order to reduce the temperature I'm trying to dynamically change the frequency of ...
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41 views

What do the benchmarks in HardInfo mean?

The program hardinfo is included by default with Lubuntu as a system profiler. It can run 6 different types of benchmarks: -CPU Blowfish -CPU Cryptohash -CPU Fibonacci -CPU N-Queens -FPU FFT ...
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22 views

Surge CP overload but low CPU usage. Got log in issue on web application when it happens. why?

I am unable to login to solaris server via GUI mode. We have checked and found that the DB/oracle session was hung up. GUI was not able to connect to Oracle DB . After clearing the hung counters from ...
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137 views

upowerd consuming 100% cpu

upowerd is consuming nearly 100% of CPU. I am currently affected by this issue on both a Lenovo Thinkpad E520 and on a desktop PC running Core i7 and Asus Z170a motherboard. Both run Kubuntu 15.10. ...
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47 views

Process scheduling and core allocation on big.LITTLE CPUs

Recent ARM chips, like the Qualcomm Snapdragon 810, seem to be using a hybrid architecture called "big.LITTLE" with cores of different architectures and speeds combined into one CPU. On a Linux (or ...
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111 views

Can rsync command run using multiple cpu?

I executed this command but it took long time when checking checksum. Load average was 1.00 at all times. Can rsync command run using multiple cpu? $ rsync --checksum -av -e ssh /usr/local/xxx/* ...
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25 views

how practical the number of cores in Android

I've often wondered how practical the cores usage in Android smartphone. I'm asking here because Android is based on Linux. I'm looking from technical perspective. The articles that I've read so far ...
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192 views

Get AMD 8320 CPU temp?

I'm looking to get the CPU temperature of my AMD FX-8320 chip. I have lm-sensors installed and I've run sensors-detect saying yes to all of the prompts. I also have the kmod system service running and ...
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90 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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85 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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335 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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107 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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154 views

Changing CPU frequency programmatically

I have seen that standard CPU Frequency driver(comes with default package with linux kernel) can change the CPU frequency at runtime, when being used under the supervision of "Ondemand" governor. ...
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285 views

Are there any alternatives to pidof? (smaller footprint)

Well, I've just found out that with extensive usage of pidof in very short intervals, the seemingly tiny tool can be a great CPU hog. (Source: top) On my older machine, it can easily reach 30 percent ...
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362 views

What's limiting my CPU usage in forked processes?

I am running some long-running programs (for scientific purposes) on a multi-core Linux box. The processes are controlled by a small daemon which restarts the next job when one finishes (I run 3-6 at ...
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375 views

How do you run CPU at turbo speed continuously

processor : 7 vendor_id : GenuineIntel cpu family : 6 model : 60 model name : Intel(R) Xeon(R) CPU E3-1230 v3 @ 3.30GHz stepping : 3 cpu MHz : 3299.670 ...
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418 views

Why is the AESni flag missing for my i5 CPU

My CPU is reported by Intel to support the AES-NI native instructions. http://ark.intel.com/products/65707 However, /proc/cpuinfo does not list the aes flag (which is what I guess is preventing me ...
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164 views

FreeBSD 9,1 - upowerd's cpu consumption off the roof and causes OS to restart

I've been experiencing a really annoying problem with a FreeBSD setup on my laptop. The setup is as follows: FreeBSD 9.1 / KDE4 desktop / Broadcom wireless 4313 through NDIS / Intel GPU with the new ...
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712 views

How can a single thread use 200% CPU usage?

From the screenshot above of htop output you can see that mysql is apparently using 204% of CPU usage (this is a CentOS server with dual quad-core Intel Xeons). However only one core (8) is doing ...
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15 views

Linux:how java applications having 1000 threads are managed by 2 CPU's os?

Linux: 2CPU's, 16gb ram Let's say, for example, tomcat having 1000 threads. How this application threads will be shared between two CPU's, and what is the value of run queue length? In my case when ...
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20 views

top command shows dnss running at 290%

We're running software on a CentOS 6.2 virtual machine and it's been crashing quite a lot lately and keeps running slow. I checked the RAM usage, but that's only using 4GB to 5GB of the available ...
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12 views

Gnome 3 on openSuse 42.1: Seemingly Random Commands Causing High CPU Usage

I am experiencing intense cycles of high CPU usage on my openSuse laptop. I have noticed my browser intermittently freezing up (and my fan speeding up) and I checked htop and this is what it looks ...
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44 views

using cpu.cfs_quota_us and cpu.cfs_period_us to limit CPU usage

There are 32 cores in a system (2 cpus each 16 cores) and I want to limit a user to use only 4 cores (100% usage for that 4 cores). There are two kernel parameter for that according to the manuals: ...
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65 views

dynadock - Crashes unexpectedly with “Fixing recursive fault but reboot is needed”

Whenever connected to my dynadock, my notebook (Linux Mint running Ubuntu 14.04.1) has crashed unexpectedly with: And if I press Ctrl+Alt+F8: [drm:intel_set_cpu_fifo_underrun_reporting [i915] ...
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22 views

High CPU usage after Version Upgrade

Not sure if is related to the version upgrade but since I have updated my Raspberry to Linux version 4.1.13+ (dc4@dc4-XPS13-9333) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG ...
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63 views

SNMP Temperature with lm sensor

I have just managed to put in SNMP the lm sensor output. However, I have an alarm due to a fake threshold of Temperature SYSTIN (see output) nct6776-isa-0290 Adapter: ISA adapter Vcore: +1.02 ...
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85 views

Change system properties(name) under linux

Sorry for the title if is not clear. What I wondering can I change somehow under linux( ubuntu / redhat ) the name of processor like in windows by registry edition? What I mean is currently when I ...
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37 views

/proc filesystem - getting useful information

I'm trying to understand the values in /proc/PID/status. I want to calculate cpu% & mem% used by PID, similar to top bash command. For Memory percentage usage I can do the following (correct me ...
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41 views

cpu temperature is higher than usual after installing xubuntu

I have installed Xubuntu 14.04 on Asus S550CB but the system becomes warmer than usual. So I tried to configure lm-sensors and saw cpu temperature is about 50 degrees. I guessed that some drivers are ...
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93 views

CPU Scheduling incredibly slow with large difference between total execution time and actual CPU time - Ubuntu Full-Disk Encryption enabled

Admittedly, I am running on a build that is no younger than five years old at this point and the system is not going to be incredibly fast. However, at the same time, the run-times I am observing are ...
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94 views

High %sy cpu usage , server is very slow

On one of the server we are noticing high %sy usage due to which server is very slow. Below is strace count for syscall. What will be the reason for high %sy usage. % time seconds usecs/call ...
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32 views

How do I gather average cpu use in the background?

I'm trying to determine if an issue I'm having is related to cpu use, but my impacted application doesn't allow me to change terminals once it's open. It there a way I could dump only the cpu useage ...
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185 views

Kill the process and restart server when memory is exceeded - bash and cron

I have a site on webfaction, using django and python. However, I have problem with memory. The problem arises, because I use external library, that can run forever (consuming much time and memory). ...
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140 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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91 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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588 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 ...