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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Total CPU usage and CPU usage under processes list is different in FreeBSD top implementation?

For some reason, overall CPU usage on my FreeBSD machine fluctuates between 1% and 85%, but the CPU usage in processes column never adds up to this amount. For example here the overall CPU usage is ...
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/proc/cpuinfo shows a single core under VirtualBox

My host machine is Windows 7, running an Intel Core i5 Processor. The Task Manager shows that I have 4 boxes under the Performance tab, which I assume to be 4 cores. However on my OEL guest (on ...
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Questions about CPU usage [closed]

How bad/normal/good is this CPU usage? Cpu0 : 14.4%us, 6.3%sy, 0.0%ni, 78.8%id, 0.0%wa, 0.0%hi, 0.5%si, 0.0%st Cpu1 : 88.3%us, 8.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 3.7%si, 0.0%st ...
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Setting running process affinity with taskset fails

I'm attempting to limit a process to a given number of CPU cores. According to the taskset man page and this documentation, the following should work: [fedora@dfarrell-opendaylight-cbench-devel ~]$ ...
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Find average CPU, vMem, sMem usage on 1, 5, and 15min

I am trying to find at time T the average CPU usage on 1, 5, and 15min, just like what you get from /proc/loadavg Same thing for virtual memory, and swap memory. I would be fine with a python ...
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248 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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525 views

How to stop CPU fan in Linux?

I use an old computer. CPU fan creates big noise. Sometimes CPU fan suddenly stops and does not work for a long time, and CPU does not get heated in these long periods, because I use very light-weight ...
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364 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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166 views

Help troubleshoot a very slow system performance (Kubuntu, intel graphics) [closed]

As the title says the performance of my laptop is simply terrible. i3 M380 @ 2.53GHz, 4GB RAM (of which more than 2GB is rarely used), intel HD graphics (to external monitor through HDMI). It takes ...
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2answers
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Hyperthreading not detected by Linux [closed]

I have a Dell server with two Intel Xeon E5645 cpus, each cpu has 6 cores, and each core is hyperthreaded (i.e. should be equivalent to two virtual cores). I installed CentOS 6.2 on this server and it ...
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64 views

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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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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293 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
333 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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226 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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3answers
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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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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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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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458 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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322 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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142 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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969 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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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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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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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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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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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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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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534 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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176 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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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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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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309 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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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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803 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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595 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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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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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
137 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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123 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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608 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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172 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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236 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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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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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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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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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, ...