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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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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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1answer
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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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1answer
37 views

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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1answer
39 views

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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1answer
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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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1answer
130 views

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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Encouraging the CPU to perform out of order execution [migrated]

I am attempting to exploit the meltdown security flaw on Ubuntu 16.04, with an unpatched kernel 4.8.0-36 on an Intel Core-i5 4300M CPU. First, I am storing the secret data at an address in kernel ...
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1answer
56 views

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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3answers
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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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Why can't run same binary on different OS

If I have 2 identical computers with the same cpu but different OS, for example Windows and Ubuntu (or some other linux stuff). Why can't I execute the same executable? Shouldn't the instruction set ...
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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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23 views

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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1answer
43 views

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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2answers
68 views

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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39 views

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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44 views

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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1answer
137 views

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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1answer
22 views

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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0answers
46 views

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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1answer
47 views

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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1answer
55 views

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
35 views

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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2answers
88 views

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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1answer
29 views

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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0answers
30 views

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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1answer
174 views

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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1answer
334 views

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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1answer
76 views

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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3answers
255 views

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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1answer
42 views

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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2answers
149 views

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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2answers
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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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0answers
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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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168 views

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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1answer
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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 ...