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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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Ubuntu 18.04 CPU governor in powersave mode getting in the way of performance

I have an Intel i7 6700HQ. Min frequency: 800 mhz Max frequency: 2.7 Ghz Max frequency with turbo-boost: 3.5 Ghz Using Geekbench 4 to stress and benchmark CPU, I got VERY different results with /sys/...
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What is the relation between IO wait utilisation and load average

Load average uses processes that are running or runnable or in uninterrupted sleep state. So do the processes in uninterrupted sleep state correspond with the %wa as per the top command? Both are ...
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Is it safe to disable clamscan and clamd services on linux server

We have a dedicated CentOS server with 8 CPUs. We often observe clamscan and clamav taking too much CPU. I have heard experts saying linux doesn't require an antivirus. If that is true, is it safe to ...
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How to increase ksoftirqd usage for testing

I have developed an application to calculate the percentage of ksoftirqd usage per CPU core and I want to test this. I am flagging an alarm if the usage is more than 50%. To test this, I need to load ...
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How to permanently configure the CPU performance setting on SLES?

We are doing a: vi /etc/systemd/system/cpupower.service [Unit] Description=CPU powersave [Service] Type=oneshot ExecStart=/usr/bin/cpupower idle-set -D 0 ExecStart=/usr/bin/cpupower frequency-set -...
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mysql taking 100% of CPU

I had a problem with my VPS like a week ago, and I had to completely reinstall it for it to work. It worked, but just for a while. Everything was alright until now, I really don't know what the ...
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Laptop fan always says it's running at 8 RPM

I have a Lenovo Legion Y520 with these specs: zjeffer@ArchLinux ----------------- OS: Arch Linux x86_64 Host: 80WK Lenovo Y520-15IKBN Kernel: 5.1.7-arch1-1-ARCH Uptime: 42 mins Packages: 1659 (...
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How to assign one process on two CPUs

I have an Ubuntu server, which has 16 CPUs. (nproc --all show me 16) I wrote a bash script named test.sh as below: #!/bin/bash while : do echo xxx done I executed it: ./test.sh >/dev/null &...
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Two identical application different cpu usages behavior

I have two openstack instance node1 - 16 vCPU / 16GB memory node2 - 8 vCPU / 8GB memory both machine behind F5 load-balancer (round-robin) and running MongoosIM application, but i am noticing ...
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Which reasons may cause low MHz of CPU

My system is Ubuntu 16.04.3. I installed it just now and executed some processes on it. I found that many processes used more than 100% CPUs. However, when I executed lscpu | grep MHz, I got the ...
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What is the logic of using $($(nproc) + 1) in make command?

I was trying to install OpenCV in Ubuntu based on few guides online. One of the guides is this one. It has the following line: make -j $(($(nproc) + 1)) The nproc returns the number of processors/ ...
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How to test two identical process with different scheduling policy and their cpu usage

what would be the best approach to compare usage of the processor (in %) for two identical processes with different scheduling policy in for example one-minute time frame. I'm pretty new to the linux ...
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Total memory vs memory per CPU vs memory per process

I have troubles understanding memory (RAM) specifications of CPUs. Just as an example, the Xeon Gold 6144 specs give a maximal memory size of 768GB. If I have a mainboard with two CPU sockets and 24 ...
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Cmd to check pids used by particular cpu's

In our environment we have applications running in servers with 0-3( total 4 cpu's). While seeing 'top' command and choosing 1 option, able to see 4 cpu's ( example: a server has 4 cpu's). In this ...
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How to set CPU freq individually?

In my understanding, we can set CPU freq by governor/policy, however, it seems a global setting for all cores. Can we set different freq for each core?
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Virtual Machine Linux OS

I have a few Linux virtual machines running on this computer, and if I look at cat /proc/cpuinfo It is able to tell me the model name for the host system. Will this affect the performance of the "...
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Does linux (kernel) support Intel speed shift?

Windows 10 support Intel speed shift. Does Linux (kernel) also support it? Speed shift related info: https://www.anandtech.com/show/9751/examining-intel-skylake-speed-shift-more-responsive-...
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How to tune Linux machine in order to improve CPU load average and CPU utilization

We are working with a huge Hadoop cluster. We have 736 datanode machines and each node has 16 cores × 2 threads. On some machines we saw CPU load average (98-128 for 5 min). After deep ...
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Disable any number of CPU cores between 1-n (where n is maximum available cores) [duplicate]

Is there any way to tune processor cores to use fixed number of cores in range of 1-n (n is the maximum number of available cores) on Ubuntu 16.04? My processor is Intel i7-7500U processor with 4 ...
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linux mint 19 cinnamon cpu temerature goes crazy!

I've just installed the mint 19 cinnamon on my acer aspire 5830TG as a second OS alongside with win7 and immediately have a very high temp readings: $ sensors coretemp-isa-0000 Adapter: ISA adapter ...
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How does the kernel assign the nice value to a process after it has been executed?

The Linux kernel implements two separate priority ranges. The first is the nice value, a number from –20 to +19 with a default of 0. Nice values are the standard priority range used in all Unix ...
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How to get maximum performance on HP Proliant server running CentOS 7?

I'm trying to get constant maximum performance on my HP Proliant server running CentOS 7. Current configuration of using intel_pstate driver which varies clock speed between 1.2GHz - 2.4GHz isn't ...
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How can my cpu frequency be above maximum MHz value in lscpu?

How can it be, that my current cpu frequency (CPU MHz) for my Intel Core2 Duo T9400M is above max MHz while being on high load? ➜ lscpu [...] Model name: Intel(R) Core(TM)2 Duo CPU ...
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How to get the average CPU usage over the past 10 seconds in bash?

I need a command that would echo the average CPU usage over the past 10 seconds in Ubuntu 18. Each of the following conditions must be met: It must be lightweight with a very small footprint, ...
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After resume from suspend, one CPU core stays in C0 state

It recently seemed like my fan was running more than average, but I didn't notice anything significant showing in top. I looked via i7zl and found that one core was staying in state C0 ~85% of the ...
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Why do I get different cpu flags in /proc/cpuinfo between CentOS 6 and CentOS 7?

CentOS 6.9 showed the following CPU flags in /proc/cpuinfo: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm ...
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AIX 7.2 Topas show high CPU

When I execute topas for a certain process, in the CPU% column it shows me 43% and jumping to 85%. When I execute: "ps aux | grep processName" The same process is at 5%. What is more accurate? I ...
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How does the CPU know if it is accessing an unallocated memory location? [closed]

Based on my understanding, when the CPU is accessing some memory location, for example if it is setting the memory location with the address of 4 to the value 100, it treats the address 4 as a virtual ...
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Examples of the damage that a buggy program running in kernel mode can make

I have read that it is dangerous for a program to run in kernel mode because it would have access to kernel memory. I am looking for realistic examples of what damage can a buggy program running in ...
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WSL Ubuntu 18.04 shows wrong Cpu_allowed mask

Ubuntu 18.04 running under WSL detects my CPU wrong: $ cat /proc/self/status | grep Cpus_allowed Cpus_allowed: 00000001 The CPU is an i7-4510U (2 cores/4 threads) so I expected: Cpus_allowed: f ...
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Check if the cpu clock speed has historically changed in RHEL6

I have a RHEL6 server running on a vmware-esxi host but no access to the host or vCenter. I need to determine if the hosting provider is using power saving features one such way is to check if CPU ...
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How to find top memory & CPU consuming process for particular time?

I have checked the sar report and found that CPU & Memory is getting utilized much more at particular time (for ex. day ago). Is it possible to find which process was taking much CPU & Mem? ...
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High CPU load average; how to find the root cause?

It is hard task to find the root cause of CPU load average many commands are used to give partial picture. I am not sure if somewhere we can find a tool that knows how many CPU's we have on machine ...
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How to get CPU “load” of subset of CPU cores?

In my environment, each job is assigned (cpuset) to a subset of CPU cores, almost exclusively. (Actually, it's done by Slurm.) Since the CPU core occupation is exclusive, can I get/calculate the 1-...
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System statistics from different utilities don't agree

I am running an Aliyun instance with 8 vCPUs to do some high performance computing, so I want to make full use of the machine. In other words, extremely high CPU usage is not a problem; instead it is ...
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CPU core is very busy and top shows 0.0 %CPU on it

This Ubuntu server is booted with CPU isolation isolcpus=0-7, so 8 cores from 16 are reserved and the only processes that use them are numbered as worker_0 - worker_7. As can be see by top's per CPU ...
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CPU usage increases on all guests if 1 guest has high usage (QEMU-KVM) [closed]

The point is that if I utilize the CPU on 1 guest, all the other guests see increase in CPU usage. I'm testing with stress-ng, but it's visible with normal workload as well. I really don't know if ...
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uptime + cpu load average [closed]

we have the follwing CPU details more lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 32 On-line CPU(s) list: 0-...
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Does it work? Ryzen 1800x and XFX RX590 on 4.15.0-46-generic?

I'm thinking on buying a Ryzen 1800x together with a XFX RX590. I've been doing some reading but couldn't get my mind clear so I thought about asking someone with actual experience on these hardware. ...
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How to know if CPU fan is ending his life?

I have laptop Dell Inspiron 15 5570 (I'm not using GPU only build in Intel graphic card) and have this issue: I have this output from dmesg: [170178.959009] CPU7: Core temperature above threshold, ...
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How does the Linux Kernel handle newer chips that patched only against Spectre Variant 1 but not Variant 2?

How will chips patched for Spectre Variant 1 and Meltdown, like Whiskey Lake and Amber Lake, handle Spectre Variant 2? I'm looking to spec out a new laptop. Currently evaluating the Lenovo x390. It's ...
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C-state in VM: needed or no?

Would it cause any difference if the cstate is enabled or not on a VM? cat /sys/module/*_idle/parameters/max_cstate So not on the hypervisor, rather on a VM. Any virtualization, question in ...
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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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1answer
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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=($5)*100/($...