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Questions tagged [cpu]

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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Unresponsive system with powersave governor on Thinkpad X1 Carbon

Using a Thinkpad X1 Carbon 2018 (6th Gen) on Ubuntu 18.10 with kernel 4.18 I notice that the system feels unresponsive even in AC mode. It's most noticable in Firefox (but not restricted to it) ...
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How do you find out if a linux machine overheated before the previous boot and was shutdown in Debian?

Today I was working on a remote machine (the likes of which I'll likely never see), and it was hung, so I told the user to restart it. The machine came up again, and I SSH'd into it, but as soon as I ...
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multi-core CPU usage

I am using the Windows Subsystem for Linux (WSL). Recently, I've been wanting to get better insight in the CPU usage of processes, but I am getting well confused. I am on a computer with 2 cores and ...
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How to analyze top command results: CPU & RAM consumption

I am working on ARM-based processor (OS version: Linux 3.4.35) and I need to analyze the processor's performance while some processes are running, by typing top command, I can see some statistics but ...
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How to isolate CPUs with cpusets from boot onwards

How I could achieve the same result with "cpuset" as with "isolcpus", since isolcpus is now deprecated. So, how could I set the first core for system tasks (like processes and IRQs) from boot onwards,...
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Counting CPU/Cores per CPU/Total Cores [duplicate]

I can't install lscpu on this host, or I would have just done that. Working on RHEL 5 here. I pulled info from /proc/cpuinfo: grep -i "physical id" /proc/cpuinfo | sort -u | wc -l 2 Returns 2 ...
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Kernel Support | Processors List

Where can I find the supported Processors for each Kernel Version? For example (KBL Processors) is only supported for Kernel Kernel 4.5
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How to restrict awk math output to 2 decimal places

My Command is below and its print Free CPU and Used CPU below format. I want to restrict awk output to 2 decimal place. grep 'cpu ' /proc/stat | awk '{usage=($2+$4)*100/($2+$4+$5)} {free=($5)*100/($...
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Distribution of threads among CPUs?

lscpu gives: Thread(s) per core: 2 Core(s) per socket: 32 When running an intensive 32-threads process, why does htop show almost 100% CPU activity on #1-32, but very little activity on #33-64? ...
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How to permanently set CPU governor without `cpufrequtils`?

Hardware: Dell Inspiron 15 Gaming 7577, model number 7577-92774. System: I am on Linux Mint 19.1; based on Ubuntu 18.04. Processor: I have an Intel Kaby Lake CPU: Intel Core i7-7700HQ. I have read ...
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Can I safely reduce CPU usage with kill -SIGSTOP?

I have 7 differents workspaces and each of them have a different purpose. But everything runs in the background... For exemple the workspace 5 with my browser is using CPU even when I'm on workspace ...
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Shell Scripting best practice to make sure script is not over utilizing memory or CPU [closed]

I have been writing shell scripts from long time but I never thought of optimizing script to make sure its not using more cpu or memory .. I am looking out for some suggestions or process with which I ...
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NMI watchdog: BUG: soft lockup lm-sensors

System board: PCEngines APU2C4 uname -a Linux demobox 4.9.0-0.bpo.8-amd64 #1 SMP Debian 4.9.110-3+deb9u5~deb8u1 (2018-10-03) x86_64 GNU/Linux I am experiencing an issue with a specific system board ...
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CPU temperatures in linux: throttling or wrong reading?

Using a Lenovo Legion Y520 with i7-7700HQ (base clock 2.8Ghz) and GTX 1050. I'm getting CPU overheating warnings in linux and it's affecting my performance in games (found in Payday 2 and CS:GO). I'...
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What counts into the cumulative CPU time for a bash process?

What counts into the cumulative CPU time for a bash process? Only when bash is parsing all kinds of commands before actually executing them, and when bash is running builtin command and function ...
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Turn off CPU turbo-boost for a process

When the CPU (Intel i5-8400) is heavily loaded, the fan seems to increase its speed and make noise. I want to eliminate the noise when running CPU-intensive backup process (backup2l program). (It is ...
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What are the benefits of using longer/shorter periods in cpu.cfs_period_us?

When you want to limit CPU time per process, you can do it via cgroups. There are two parameters that can do the job: cpu.cfs_period_us and cpu.cfs_quota_us. There's some info on the parameters here: ...
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linux top load average seems too high

Following this https://unix.stackexchange.com/a/279354/108702, I ran; lscpu | grep -E '^Thread|^Core|^Socket|^CPU\(' CPU(s): 8 Thread(s) per core: 2 Core(s) per socket: 4 Socket(s): ...
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Find number of cores available in a given node

I need to fix the following piece of code. The code aims to determine the number of cores available in a given node. Step 1: Get the number of cores with TC=$(grep -c process /proc/cpuinfo) Step 2:...
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Launch a program to only specific resources

Question: How can I launch a program such that it only uses X ram and Y CPU cores, etc? I happen to be using Ubuntu in this case, but since I often am on other distros, I need a general GNU/Linux ...
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sensors reports negative CPU temperature for Ryzen

sensors used to work well for me but since upgrading to a Ryzen 2700X the readings don't make sense. nct6779-isa-0290 Adapter: ISA adapter Vcore: +0.56 V (min = +0.00 V, max = +1....
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Find process source which executing python scripts [closed]

From last month some process is executing python scripts on my server with centos 6 with LAMP stack which are nothing but spam bots and eating server resources. Please check image below, How do I ...
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1answer
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What option argument can I give to `cpulimit -l` when I want a process to have unlimit cpu usage?

In cpulimit -l, --limit=N percentage of CPU allowed from 1 up. Usually 1 - 100, but can be higher on multi-core CPUs. (mandatory) What option argument can I give to -l when I want a process ...
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Linux + how to know which CPU Cores was active last day

recently , we upgrade our redhat server ( version 7 ) from 4 CPU CORE to 32 CPU CORE is it possible to know which CPU was triggered during last day ? I mean how to know if the additional CPU that we ...
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Script - Cutting various lines and sort them

i want to sort the process of one user by the percentage of cpu used. I tried this ps aux|tr -s " "|cut -f3 -d " "| sort -| grep "user" > file name does this work?
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Mate panel keeps the CPU at 100%

I just upgraded the tumbleweed version and everything goes well so far, but a couple of days ago the mate session started to be unresponsive and the top and bottom panels freezes. I disabled the ...
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Why both “/sys/devices/cpu” and “/sys/devices/system/cpu”?

Under /sys/devices, whys is there both /sys/devices/cpu and /sys/devices/system/cpu rather than just one or the other?
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online processor in nproc

When I run command $ nproc --all 4 DESCRIPTION Print the number of processing units available to the current process, which may be less than the number of online processors It ...
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CPU thermal throttle counters

In each CPU device directory (/sys/devices/system/cpu/cpu*) there is a directory called thermal_throttle that contains two counters called: core_throttle_count package_throttle_count What are the ...
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Overheating while running Linux in Laptop

I've been running into issues while running Linux Mint MATE 19 64-bit in my laptop (Toshiba L750). It's installed in a SSD drive and there are 16GB of RAM installed. I purchased a SSD to move to ...
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Why is only Linux affected by the Bay Trail cstate bug?

I recently tried to install Linux (I tried Ubuntu and Arch) on a system using a Pentium N3510 (Bay Trail) processor and initially failed with random hangs and sluggishness. Trying out various things, ...
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lscpu shows incorrect number of cpus [closed]

I've just checked cpu informations on one of ours servers and I am a little bit confused. Intel says that this model has 28 cores, whereas lscpu shows only 2. Am I missing something? Virtualization? ...
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Kernel module shows me 8 processors instead of 4 for Intel i5-2500K

My question mostly about hardware, specifically the Intel i5-2500K CPU which Intel describes as having # of Cores 4 # of Threads 4 Linux shows me 4 processors: $ cat /proc/cpuinfo | grep ^...
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Why does cpuinfo show only 2 processors? [duplicate]

I'm running the following command: cat /proc/cpuinfo | /bin/egrep 'processor|model name|cache size|core|sibling|physical' Which gives this output: processor : 0 model name : Intel(R) Xeon(R) CPU ...
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What exactly does “Illegal instruction (core dumped)” mean? [duplicate]

I see a lot of solutions to resolving the problem exemplified by Illegal instruction (core dumped) But, I'm wondering what exactly that means? What generates that error, and what's the root cause ...
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Actual compilation differences between CPUs

For a project I intend to compile various *NIX OSs and their relative packages with different CPUs in order to maximize optimization and performance for specific systems. In order to save time and ...
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cgroups: Is it possible to limit cpu usage by process name instead of by pid

As we know, cgroups can limit cpu usage of processes. Here is an example: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 30142 root 20 0 104m 2520 1024 R 99.7 ...
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Understanding output of lscpu

You can see the output from lscpu command - jack@042:~$ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 56 On-...
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How to calculate the number of vcores on a Linux machine

In my Linux machine I have 32 vcores. And from lscpu, I can see same. For my CPU, "Thread(s) per core" is 2. So does it mean that I have actually 64 vcores?
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Intel Pstate frequency limits are overridden

Problem : Run all core on minimum CPU frequency on Intel pstate driver on ubuntu 14. cpupower frequency-set --governor performance --max 1300MHz I am trying to run my cpu cores on different ...
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1answer
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Change the cpufreq driver from intel pstate to acpi

I am trying to disable the intel pstate cpufreq driver and replace it with acpi to get maximum cpu control. I tried this. vim /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="intel_pstate=disable quiet ...
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Scale down to a specific frequency on Ubuntu Linux 14 w/ Intel CPU

I am trying to scale down one of the CPU frequencies. I am using Ubuntu 14 and Linux kernel 4.4. I want to scale down the cpu3 frequency to 1.2 CONSTANT (no throttle). Things I have tried: I want ...
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3answers
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What does “m” mean in mpstat?

I check the manual of mpstat it states: The mpstat command writes to standard output activities for each available processor, processor 0 being the first one. Global average activities ...
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1answer
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What is CPU min MHz in lscpu output?

There are CPU MHz, CPU max MHz and CPU min MHz in lscpu output. What are they mean? Especially the CPU min MHz? We can think CPU max MHz is maximum CPU frequency and CPU MHz as current usage. Why ...
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Not all CPUs entered broadcast exception handler Kernel Error

I've been dual booting Ubuntu on my laptop and for a few months its been perfect. Today however when booting up this error has appeared, and despite numerous restarts nothing has resolved it: Kernel ...
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1answer
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Rolling back Intel-microcode updates and computer speed

I assume that Debian package intel-microcode packages gradually correct the various spectre and meltdown issues. From what I understand about these problems, the only way to correct them on existing ...
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1answer
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How is runq-sz counted in sar?

I would like to ask question about the output from sar -q . I appreciate if someone can help me out with understanding runq-sz. I have a system which cpu threads are 8 cpu threads on RHEL 7.2 . [...
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1answer
887 views

What Linux kernel version(s) have a fix for the L1TF (Foreshadow) exploit?

Foreshadow is a new speculative execution exploit targeting Intel's SGX on Core chips What Linux kernel version(s) contain a fix for the L1TF exploit?
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Run factor in parallel

how to run Linux's factor in parallel, i.e. utilize all CPU cores? I have tried to run factor <prime number> but unfortunately only one CPU core is being utilized.
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How does ps measure %CPU per process (and can this be changed?)

When doing ps -r -e -o pcpu=,comm=, the % CPU displayed per process, over how long time is this value measured? Is it one second? The manual page does not seem to mention this. And a follow-up ...