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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401 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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462 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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310 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 (t=...
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35 views

How to determine how much time a process is blocked waiting for networking (socket) activity?

We are having issues with high load (top and uptime) but high CPU idle. Usually, that means high IO wait but that's also low. I believe IO wait typically does not include time a process is blocked ...
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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 2.6.32-042stab090....
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134 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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320 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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332 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 'turn-on-eldoc-...
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36 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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387 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]] *ERROR*...
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63 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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692 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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162 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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20 views

Marking TSC unstable due to check_tsc_sync_source failed

My dedicated server has been hanging it out (or just turning off) very often sometimes more than a day, apparently for no reason (according with the technical support department). After that, the only ...
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94 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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24 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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75 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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215 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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26 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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224 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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94 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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107 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 Adapter:...
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377 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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114 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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170 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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310 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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396 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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424 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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446 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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166 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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739 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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11 views

Fan starts when watching videos through browser plugins on Macbook with Arch

On a Macbook Air (2012) running Arch, after watching a show on Netflix with Google Chrome for ten or 15 minutes, the fan starts; this hardly ever happened with Mac OS. Can something be done?
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18 views

Fast file access for many threads doing read / write operations?

I have a disk with a lot of data on it and I want to write some code such that thousands of threads can operate on the data. Each thread would work on its own individual file. This will speed up ...
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11 views

TCP/UDP socket in order to put on hold processes

I'm working on some bash scripts which will solve "The dining philosophers problem", in order to do so I created two scripts, run.sh and philosopher.sh . In run.sh I run n instances of philosopher.sh ...
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32 views

Ubuntu guest CPU steal 99.7 %

I'm currently running a VPS which appears to have some very strange problems. Running top gives me 99.7 % CPU steal. It's always the same value and started 3 days ago. The same thing happened a while ...
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43 views

rcu_sched self-detected stall on cpu after amd driver problems

I made a mess with my VGA driver (I have a Hp 455 probook) because SDL and openGL was having issues to create instances. After some driver reinstallations I decided that was time to reboot, but ...
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35 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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0answers
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 9GB....
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36 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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142 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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88 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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26 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 linaro-1.13.1+...
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72 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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103 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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45 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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106 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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0answers
33 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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220 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). ...