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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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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Comparing Windows and Linux machine hardware

I have to compare Linux and Windows machine hardware? In windows system, I can open the My computer properties and see the details like processors, RAM Hard disks etc. Through task manager, I can see ...
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163 views

why is my laptop-mode configuration being ignored?

I am running Debian GNU/Linux Jessie (testing) on my laptop. I enabled the systemd laptop-mode service: $ sudo laptop_mode Laptop mode enabled, active [unchanged] and in my ...
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245 views

What does a computer actually do with its spare CPU cycles?

When a computer is not running at full load, in the context of Linux, what does it actually do? Between scheduled threads, if there is nothing to do, does it spin wait? Does it enter some sleep state? ...
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2answers
304 views

How to compare usage of memory by Window Managers?

I'd like to test a few window managers to see which of them takes less memory and CPU in certain time period (so is better choice for older computers). I'd like to make the tests myself (not to read a ...
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159 views

File to access for CPU load average on AIX

Is there a file with the load average in it on AIX? I'm looking for something like Linux's /proc/loadavg.
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/proc/cpuinfo “cache” category: L1, L2 or total?

When I look in /proc/cpuinfo, one of the lines tells me I have 6144 KB of cache. Is this L1 cache, L2 cache, or the sum of both of them? In any case, how do I find out how much L1 and L2 cache my ...
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623 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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231 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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216 views

CPU Frequency Scaling Monitor: No passwd, all cores at once

I use MATE 1.6.2 and CPU Frequency Scaling Monitor 1.6.2. I would like two things: Get rid of the need of the root password to change the CPU settings. To affect all cores at once. The problem is ...
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259 views

How to calculate per CPU load

Is there any C API to calculate per CPU load? /proc/loadavg gives the CPU average load for all available CPUs and /proc/stat doesn't mention anything about active processes per CPU. How can I obtain ...
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225 views

KVM reports strange CPU usage peaks (bash infinite recursion)

On a KVM machine running Fedora 20 I ran ulimit -s unlimited (this removes limit on stack size) and an experimental torturing testing script. All this script does is just infinite recursion: ...
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117 views

Lower cpu performance in Linux [closed]

I have a problem with my CPU performance in Linux. I have a laptop, Toshiba Satellite C660-101. Despite the fact that the CPU works perfectly fine in Windows 7, Linux has some serious issues. ...
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755 views

Get CPU usage for single process

I've got a problem getting a real-time CPU usage of a single process (by its PID). I'd like to setup a watchdog for the CPU usage of a process because it's suddenly reaching 100% of the CPU usage ...
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4answers
11k views

Number of processors in /proc/cpuinfo

While i was learning about cpu load i came to know that it depends on numbers of core. if i have 2 cores then load 2 will give 100% cpu utilization. So i tried to find out cores.( i already know that ...
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17k views

What are software and hardware interrupts, and how are they processed?

I am not sure if I understand the concept of hardware and software interrupts. If I understand correctly, the purpose of a hardware interrupt is to get some attention of the CPU, part of implementing ...
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362 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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99 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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8k views

Top “id” is using 50-99% of CPU

My i386 Lubuntu install is running with a constantly 100% CPU. Using top I have diagnosed "%id" as using up a lot of CPU, usually between about 50% and 99%. Why is this happening, and how can I stop ...
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631 views

NVIDIA: could not open the device file /dev/nvidia0 (Operation not permitted)

When I try to run chrome/ium on command line it says NVIDIA: could not open the device file /dev/nvidia0` (Operation not permitted) I don't know whether its related with high CPU usage on ...
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2answers
14k views

Understanding %CPU while running top command [duplicate]

I am trying to understand what does %CPU means when I run top. I am seeing %CPU for my application as 400 or 500 most of the times. Does anyone knows what does this mean? What number is a high ...
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3answers
5k views

kswapd0 takes 99% to 100% CPU in RHEL 6.3

I have 5 systems on which I have just installed RHEL6. System configuration is CPU-i7 HDD-500 GB RAM-2 GB Swap- 4 GB I have installed the same software's and all the configuration as per ...
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615 views

What does % utilization mean in htop if only 1 process can execute at a time?

I see that the htop command reports respective the % of utilisation of each CPU core and also that of the processes. We know that only 1 process can execute at a time in the CPU. How is it possible ...
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detect process eating cpu without: top, htop, ps?

I went thru a problem where I could only guess what process was eating the cpu. My cpu usage was about 80% for all cores at psensor. I tried htop, top and ps -A -o pcpu,pid,cmd --sort +pcpu (the ...
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290 views

CPU percentage of a single process

How do I get the average CPU percentage (for every second) consumed by a single process since it starts until it ends (exists)? Could I make this with Top?
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153 views

What's the correct value to base the maximum number of CPU's to sched_setaffinity to?

I have some confusion as to what's the correct value to use for the number of CPU's I can use to make a CPU_SET for a sched_setaffinity call on my system. My /proc/cpuinfo file: processor : 0 ...
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106 views

Find out if CPU supports dynamic speed setting

I need to find out in my script if a (potentially legacy) CPU supports dynamic speed setting, and eventually get value of maximum and current speed. What makes it more complicated is that I need to ...
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2k views

Does BIOS read directly the bootloader or load it into RAM?

I'm trying to understand the very first steps of the boot process. The CPU read the BIOS It reads a fixed address instruction It will jump to the first BIOS instructions address It will execute ...
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Intel Xeon stuck at 800mhz CPU Freq on RHEL 6.5 [duplicate]

Currently running into a headache trying to figure out why my CPU speed is stuck as such a low frequency. After doing some research, I found that cpuspeedutil does actually control the state of the ...
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1answer
175 views

Check SSE3 support from bash?

Is there a way to check whether or not the current system supports SSE3 from a bash script? I'm currently writing an installer script, and the program in question has an alternate version that takes ...
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3answers
8k views

Bash script that automatically kills processes when CPU/memory usage gets too high

I have created a script that kills processes if CPU and/or memory usage hits 80%. It creates a list of killed processes when this happens. What can I do to improve it? while [ 1 ]; do echo echo ...
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3answers
483 views

Is there a way to make your process use less CPU?

I want my device to use less CPU to save battery. I have a program that uses a large amount of it. nice won't help as all it does is change scheduling when CPU is at %100, while I don't want it to get ...
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581 views

CPU Placement in KVM

I have a configuration of KVM guests where the cpu placement is configured as follows: <vcpu placement='static'>1</vcpu> Now since I don't have a cpuset specified I was reading libvirt ...
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402 views

Slow down CPU when it heats up

I run Gentoo Linux on my laptop. I have an issue, though, where if I'm building some very large piece of software (as I do fairly frequently, since the purpose of this laptop is development), the CPU ...
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2k views

High Idle CPU / Low CPU Load average

After removing APC (alternative php cache), I noticed that there are less pagination access and less dirty pages but in the same time: High idle CPU Very low CPU load (relatively to the time before ...
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2answers
1k views

What does it mean exactly when a processes “Time” has stopped in top?

I'll be looking into why we're getting critical swap alerts, and I'll find something like: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 14683 user1 30 10 16.0g 772m ...
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performance monitoring

Is there some performace monitoring tool which would run in background gathering info about all system activity? Somethimes my system (Arch linux, 32 bit) slows down terribly and the top utility ...
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1answer
102 views

Minimizing hardware interrupts

I am using a modified Linux kernel as a soft real-time OS, on a system that has an architecture like this: CPU1 and CPU2 have 8 cores each. I have 4 processes that need to be run with minimum ...
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1answer
97 views

How the network packets are transferred to the memory on linux?

Is there some command or tool for monitoring network packets and how those packets are handled by the memory and than proceeded to the CPU on linux platform? Using tcpdump I can capture many apache ...
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2answers
443 views

How to get CPU Percentage as a Counter?

I would like to monitor total CPU utilization percentage as a counter. The reason I would like it as a counter is that data won't be lost between samples (and I can have the graphing side calculate ...
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130 views

CPU and RAM monitorization by parent id

I'm trying to monitor the CPU and RAM usage (in % of total for example) of a given process wich may spawn several processes. The parent process is /bin/rscw so I get its pid by ppid_bl=$(ps -ef | ...
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169 views

Having an independent console to kill rogue process?

Sometimes a flash plugin starts using all the mem and CPU or an app is also behaving "naughtily" and my system starts to crawl until i finally get a terminal with htop up and kill the rogue process, ...
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1answer
105 views

What happens to the files when they are being decrypted?

I have the server's webroot directory mounted on a partition which is being protected with LUKS encryption. I want to know what happens to the files within when that partition is being decrypted. Does ...
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cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options - 1. set up a cron-job or, 2. implement a loop with sleep in the script itself. Question: ...
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1answer
3k views

How can I monitor CPU usage by user?

I need to monitor CPU usage by users of two servers' (Ubuntu and CentOS). For example: user1 5% user2 10% ... Is there a tool similar to top or htop that can do that?
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1answer
785 views

How to set the CPU freq. in Linux?

I'm using this ARM9 SAM9G25 embedded system, that when switched on, is only online for a few seconds and because I want to speed up the whole process, I'd like to check the CPU frequency, and set it ...
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146 views

Why my cpu spend so much time on system? [closed]

top - 08:58:42 up 20 days, 8:23, 1 user, load average: 67.17, 58.94, 62.75 Tasks: 630 total, 40 running, 524 sleeping, 0 stopped, 66 zombie Cpu(s): 57.3%us, 41.6%sy, 0.0%ni, 0.0%id, 0.0%wa, ...
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Top c - CPU usage >200% Will it Crash?

I would appreciate some advice from your experience. My main concern is I really REALLY do not want to cause the computer server to crash. The question is, I am running a program on a Linux computer ...
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363 views

Determine the intel CPU family for C compiler?

I am checking the CPU information on a Linux server, and tuning options of the Intel C compiler icc for my C code running on the server's specific architecture. I am thinking about choosing the value ...
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1k views

Mint fan control

I've installed Mint 15 on my Alienware m14x and can't figure out one thing. For some reason CPU overheats and fan does not respond to that. It always stays calm and quiet. How exactly I can change ...