The cpu tag has no wiki summary.
22
votes
1answer
1k views
High CPU usage with CFS?
I asked a previous question to try and isolate the source of an increase in CPU usage when moving an application from RHEL 5 to RHEL 6. The analysis that I did for that seems to indicate that it is ...
19
votes
3answers
971 views
How to limit resource usage to save CPU+RAM for a certain process?
I have a dev server on which sshd sometimes stops working because the machine runs out of RAM. Yes we are running low on memory and upgrading is not a feasible choice right now. What I want to do is ...
18
votes
2answers
6k views
What do the flags in /proc/cpuinfo mean?
How can I tell whether my processor has a particular feature? (64-bit instruction set, hardware-assisted virtualization, cryptographic accelerators, etc.) I know that the file /proc/cpuinfo contains ...
14
votes
1answer
14k views
In Linux “top” command what are us, sy, ni, id, wa, hi, si and st (for CPU usage)?
When I issue $ top in linux, I get a result similar to this (see here).
One of the lines has CPU usage information represented like this:
Cpu(s): 87.3%us, 1.2%sy, 0.0%ni, 27.6%id, 0.0%wa, ...
13
votes
2answers
432 views
Is it possible to limit how much CPU power a process can take?
I'm wondering, is there way to tell a process how much processor power it can take?
The problem is I'm converting video with Arista (video converter) and I'm annoyed by the fan running like crazy, ...
13
votes
3answers
1k views
How can I set the processor affinity of a process on Linux?
The question is all in the title: How can I set the processor affinity of a process on Linux?
12
votes
5answers
511 views
Is there a way to limit overall CPU consumption
My laptop (an HP with an i3 chip) overheats like crazy every time I run a resource heavy process (like a large compilation, extracting large tarballs or ... playing Flash).
I am currently looking ...
11
votes
3answers
1k views
How can I have 400% CPU occupied on 2 cores
I understand that Σ(%CPU) ≤ logicalcores*(1+ε) (where ε is measure and rounding error). But, how can I have on a 2 core system 2 different processes, each taking 200% of CPU (as measured by htop)?
...
8
votes
3answers
2k views
How can I receive top-like CPU statistics from the shell?
I'm trying to get an accurate read of my used CPU (in percent) from top. This is the command I'm running for testing:
top -n1 | awk '/Cpu\(s\):/ {print $2}'
This returns:
10.7%us,
Which is the ...
8
votes
1answer
2k views
Isolating cause of higher CPU usage on RHEL 6 vs RHEL 5
I'm currently looking to move our system from RHEL 5 to RHEL 6, but I've run into a snag with unexpectedly high CPU usage on the RHEL 6 machines. It appears that this may be due at least in some part ...
8
votes
2answers
495 views
lshw and lscpu disagree on caches - which is right?
I am trying to find out specifics about caches (in particular which caches are shared between cores and which are not) and have stumpled onto a inconsistency.
sudo lshw says
*-cache:0
...
7
votes
3answers
4k views
How to check that AES-NI is supported by my CPU?
Howcan I check if my CPU supports the AES-NI instruction set under Linux/UNIX.
7
votes
2answers
326 views
Overheating results in system shutdown
I have been having an overheating issue which makes my laptop shutdown immediately. Is there anyway to monitor the temperature from the sensor and scale down the CPU frequency to avoid that problem? ...
7
votes
3answers
3k views
Why is kworker consuming so many resources on Linux 3.0.0-12-server?
Last Friday I upgraded my Ubuntu server to 11.10, which now runs with a 3.0.0-12-server kernel. Since then the overall performance has dropped dramatically. Before the upgrade the system load was ...
6
votes
2answers
258 views
Why do I have four CPUs listed in /proc/cpuinfo?
When I bought my Lenovo Thinkpad 520, it had Windows installed. I promptly cleaned that out and installed Fedora 16. I recently visited the /proc/cpuinfo and, much to my surprise, discovered that it ...
6
votes
2answers
171 views
How can I chase a program who is rising up my laptop's temperature?
After 40 days of non-upgrading I came back from a trip and I decided to dist-upgrade my Debian Sid box. Everything went fine but after rebooting I noticed that the temperature was 15°C over its ...
6
votes
2answers
6k views
Limit process to one cpu core
How to limit process to one cpu core ?
Something similar to ulimit or cpulimit would be nice. (Just to ensure: I do NOT want to limit percentage usage or time of execution. I want to force app (with ...
6
votes
2answers
620 views
Java problem - nearly looks like a virus?
I have a weird problem since about a week. When I wake up my computer from suspend, a java process starts and consumes about 170 % CPU capacity.
I analyzed the java process a bit: it connects to ...
6
votes
1answer
847 views
Is the sum of all PIDs “utime” the total system utime?
In order to measure a user's total CPU time, I'm using the "utime" field out of /proc/[pid]/stat:
utime %lu Amount of time that this process has been scheduled in user
mode, measured in ...
6
votes
2answers
2k views
Understanding top and load average
I'm observing a high load average an certain machine (about 9) in all three load fields. I understand load as the number of processes in state "run" / currently desiring CPU time. Am I correct at ...
6
votes
1answer
181 views
Can I run multiple cores at different clock speeds?
I see the cores on an Intel i5 machine I'm looking at can only be run at the same clockspeed: /sys/devices/system/cpu/cpu1/cpufreq/related_cpus lists all of the CPUs. Setting cpu1's clockspeed changes ...
5
votes
2answers
3k views
Run process with higher priority
I want to run mplayer with higher priority than any other processes, including the IO-processes. How can I do that?
5
votes
2answers
2k views
How can I know which IRQ is responsible of high CPU usage
I've moved a server from one mainboard to another due a disk controller failure.
Since then I've noticed that constantly a 25% of one of the cores goes always to IRQ however I haven't managed myself ...
5
votes
1answer
300 views
How to find out how many cores (including emulated via HT and such) are avaliable to user?
I wonder how to get how many cores (including emulated via HT and such) are avaliable to user via bash shell-script command?
5
votes
2answers
387 views
How enable safeguards for CPU temperature
My desktop has a nasty habit. When I have several high intensity applications running and my CPU is at maximum usage for a period of time, the core temperature rises and my computer auto-shuts off.
...
5
votes
2answers
1k views
Get CPU utilization stats from C program
I want to read the CPU utilization stats from a C program, I am interested in the percentage of use of CPU, steal time etc. These stats are shown in the 3rd row from the top command.
I tried to parse ...
5
votes
1answer
2k 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 ...
5
votes
2answers
821 views
VirtualBox guest: 16 CPUs detected but only 1 online
I am running VirtualBox (using the Qiime image http://qiime.org/install/virtual_box.html)
The physical hardware is a 32 core machine. The virtual machine in VirtualBox has been given 16 cores.
When ...
5
votes
1answer
245 views
Loading speedstep_centrino kernel module
Because of a noisy fan in my laptop, I need to change CPU frequency and for this task I need to load the appropriate kernel module.
The CPU in my laptop Acer TravelMate 4002WLMi is:
$ cat ...
4
votes
4answers
292 views
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 ...
4
votes
3answers
2k views
How to find which Process is causing High CPU usage
Is there any way to find out from terminal which process is causing high CPU Usage ?
It would also be useful to order processes in descending order of cpu Usage
4
votes
2answers
421 views
Xorg increases cpu usage over time
I've had quite a strange phenomenon with Xorg for some time now: After logging in to my laptop (specifics below) the cpu consumption of Xorg increases monotonically, even if the computer is idle and ...
4
votes
3answers
477 views
On Ubuntu Linux, is it normal for mandb to run continuously (apparently in the background)?
I have access to a Ubuntu Linux node at my institution. The nodes are shared among the group, but typically I am the only person who uses this particular node.
I am running a calculation in parallel ...
4
votes
1answer
2k views
Why does top report the incorrect CPU usage?
I have a machine with Intel(R) Xeon(R) CPU E5520 visible as 16 logical cores (8 with HT). If I run something to eat CPU time (single threaded) top correctly reports 100% CPU usage for the process but ...
4
votes
2answers
1k views
Slow down the CPU
I tried to slow down my CPU with powernowd and cpufreq-selector. I hoped that with lower frequency it will be less hot and I won't hear my fan every time I will run internet radio.
I used the ...
4
votes
4answers
417 views
script for logging all the stats for a particular process
I want to monitor CPU usage, disk read/write usage for a particular process, say ./myprocess.
To monitor CPU top command seems to be a nice option and for read and write iotop seems to be a handy ...
3
votes
2answers
1k views
How come I installed Ubuntu 64 bit on a Pentium 4 machine?
I have just tried booting the Ubuntu 10.10 64 bit live USB on this machine and to my amazement everything works fine. I even installed the system, after which I checked with uname -a and the result is
...
3
votes
2answers
492 views
How does load average work with modern CPU's?
My understanding of load average lead me to be quite shocked with my current system. The CPU in my workstation is an i7 with hyperthreading enabled, and cat /proc/cpuinfo produces 4 'cpu's.
That all ...
3
votes
3answers
299 views
Invoking CPU Stress
Looking for an app or tool to invoke CPU usage on my virtual Linux and Unix guests.
I found the app "stress" from a post on Stackoverflow, but curious what the Unix/Linux crowd would recommend.
3
votes
2answers
266 views
How to identify if there is some power saving setting that powered down a processor in Linux
I have a linux server that apparently has two Intel Xeon X5670.
/proc/cpuinfo shows 12 CPUs but dmidecode shows only one CPU and the other one is in the Unpopulated status like it is showing that ...
3
votes
2answers
875 views
How to get information about word, address size, address bus size, data bus size and instruction bus size?
I was wondering how to get information about the following things from the command line in Linux:
word (i.e. the size that the CPU can process at one time, which may not be the OS bit-depth),
...
3
votes
2answers
225 views
How can we use the command 'top‘ to monitor the total CPU usage and each processor usage simultaneously?
You know that we can use the command top to monitor the real-time CPU usage and toggle the result display to the per-processor view by pressing key 1. The disadvantage of it is you can only monitor ...
3
votes
2answers
725 views
Program to test CPU load and process priority
I am running some test on Amazon EC2 instances and we want to make the CPU always busy at above 80%.
What I have is a program main that needs to run in high priority and I want to launch another ...
3
votes
1answer
731 views
Why Process CPU % Usage larger than Total CPU Time
When I run the TOP command, a process shows 1208% cpu usage and the total CPU usr time is 81.7% with IRIX mode on. When I change to IRIX mode off, the process shows 99% cpu usage and the total user ...
3
votes
2answers
347 views
Will enabling Hyper-Threading create two virtual half-speed processors?
If I enable Hyper-Threading for my netbook which has an Intel Atom (1.6 GHz) will the kernel see two virtual 800 MHz processors?
3
votes
2answers
59 views
CPU usage of KVM
I have a linux host with 4 KVM linux guests. All the guest are pretty much idle, having a load of <0.1 inside the guest.
Now, if I do a top on the host, each KVM process is using something about ...
3
votes
1answer
49 views
How to measure the clock pulse of my computer manually?
My PC has two processors, and I know that each one runs at 1.86 GHz. I have just read about clock cycles and I only have a (very) rough understanding, so I apologize beforehand if my question is so ...
3
votes
1answer
374 views
Do I have PCLMUL instruction set support?
Here are the flags from /proc/cpuinfo:
fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc ...
3
votes
1answer
479 views
Only one CPU core is active on Fedora 16
I've upgraded from F15 to F16 and noticed that I have a problems with hardware detection. Upon loading I can see message like
...
CPU#1 not responding
...
on the screen. It disappears and I can ...
3
votes
2answers
571 views
How to find if hyperthreading is enabled on FreeBSD
Is it possible to find out if hyperthreading is enabled within the BSD kernel of a given machine without watching the boot up sequence?
