Comments on: How do I Find Out Linux CPU Utilization?

By: MICHAEL

MICHAEL — Fri, 06 Jan 2012 18:57:53 +0000

SO LETS SAY I FIND OUT WHAT IS USING ALL MY CPU AND KEEPING IT RUNNING AT 100%. I FIND OUT THAT IT IS NOT A PROCESS THAT I START UP KNOWINGLY. HOW DO I STOP IT FROM LOADING ON NEXT REBOOT? MY COMPUTER RUNS SO SLOW DUE TO THE CPU RUNNING AT 100% CONTINUALLY. I WANT TO FIX THIS. AT FIRST I THOUGH IT WAS DUE TO INSUFFICIENT MEMORY SO I REMOVED WINDOWS AND INSTALLED LINUX. I ALSO DOUBLED MY MEMORY. NOW I AM AT 512MB BUT IT STILL RUNS THE SAME AS IT DID WITH 256MB.

By: TeeCee

TeeCee — Wed, 04 Jan 2012 20:11:21 +0000

@mkdizajn,

I would guess from the numbers that sda and sdb are 1TB drives. Sine it appears to have read 1TB from sda and written it to sd, mygues is t thiis the mirrorin process. After yreboo, the nunbs shod even out.The total reads on sda and sdb should add to dm-1 and the writes should be the same.

By: mkdizajn

mkdizajn — Tue, 03 Jan 2012 10:33:00 +0000

Hi,

this is my output from iostat command:

Linux 3.0.0-14-generic (k1-desk) 	01/03/2012 	_x86_64_	(4 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           3.67    0.02    1.51    0.62    0.00   94.18
Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda              31.60     14245.90        85.57  979239785    5881884
sdb              30.24         0.01     14285.26        976  981945348
sdc               1.47        20.83        18.15    1431840    1247465
dm-0              5.08        37.71        85.57    2592093    5881884
dm-1              4.96        37.70        85.57    2591693    5881884

this is very interesting because sda and sdb are same disks in mirror raid, lower named dm-1.. does this mean that disks in my raid work that way,,, one reads data, other write it ? … strange.. but makes my head think about that :)

By: Roberta

Roberta — Fri, 16 Dec 2011 19:47:47 +0000

Great post! I finally understand how to check and analyze a little better Linux CPU utilization. Many thanks! You rocks!

By: surjan

surjan — Wed, 21 Sep 2011 06:45:16 +0000

Nice article and equally good comments suggesting the new commands.
I can see some sar files inside /var/log/sa/. I can see a block containing the CPU %user %nice %sys %iowait %irq %soft %steal %idle values. Is there some way to see memory utilization in the same file, memory utilization per process or as whole.
Please help

By: Roel

Roel — Wed, 27 Jul 2011 02:03:23 +0000

Nice article – this helped, thanks.

By: Si Em

Si Em — Mon, 11 Jul 2011 10:28:34 +0000

Could you kindly descripe more detail about the below command. For example, if use command number 2 “nohup”, what directory should i used? Local directory or server directory? Thank in advance for your kind.

To get multiple samples and multiple reports set an output file for the sar command. Run the sar command as a background process using.
# sar -o output.file 12 8 >/dev/null 2>&1 &
Better use nohup command so that you can logout and check back report later on:
# nohup sar -o output.file 12 8 >/dev/null 2>&1 &
All data is captured in binary form and saved to a file (data.file). The data can then be selectively displayed ith the sar command using the -f option.
# sar -f data.file

By: sachin

sachin — Tue, 28 Jun 2011 09:43:51 +0000

how to check cpu utilization past 2 days

Please help me

By: RapidSpeeds

RapidSpeeds — Sat, 07 May 2011 15:44:52 +0000

Nice guide, very well written and documented.

Will direct anyone here should any such questions arise from one of our customers.

Thanks.

By: Taher

Taher — Wed, 04 May 2011 22:01:08 +0000

Is there a way for me to see sar results for yesterday from the default log?
( By default it only shows from midnight of today . Note: I am not explicitly running or saving it )

Thanks .

By: Kilroy

Kilroy — Fri, 01 Apr 2011 06:10:08 +0000

to be more specific i was using *sar and found all the data i wanted and more but realized that i needed more Graphical data. could anyone suggest which direction i need to move to get this done?

By: Kilroy

Kilroy — Fri, 01 Apr 2011 06:00:50 +0000

Great article!!! thanks
although i have a debian squeeze box without X GUI installed although i’d like to have graphical reports on performance statistics like CPU%, memory usage etc.. is there any tool or command i can use to get this done? using systat i noticed im getting volumes of text data and its quite time consuming to search for specific data. im quite new to this could anyone help me out

Thanks in advance

By: Lohith

Lohith — Tue, 22 Mar 2011 09:31:08 +0000

Hi ,
I am running mpstat -P ALL command and calculating the CPU utilization values. but i want to calculate the cpu utilization values of another CPU from the one that I am working from and report the values of the same to other module that is working on in my processor ..Is it possible? Please let me know ..This is a urgent requirement..

By: Mani

Mani — Wed, 26 Jan 2011 18:08:31 +0000

Great article.. Also please consider mentioning about vmstat tool. It is another great tool..

By: Sharad

Sharad — Mon, 10 Jan 2011 12:26:17 +0000

This helps, thanks!

By: Dawn Alphonse Jose

Dawn Alphonse Jose — Mon, 18 Oct 2010 11:40:02 +0000

how can i resolve this issue of CPU utilisation in my linux server.

By: venkat

venkat — Fri, 17 Sep 2010 16:56:41 +0000

Hi,
i have a query regarding CPU utilization and CPU percentage.
What is mean by CPU percentage?
Basing on what parameter we can calculate CPU percentage.
On my AIX server having 4 cpu’s shows below values for each 15 min interval.

system cpu time is 4%, User cpu time is 90% idle cpu time is 6%

and CPU percentage of all the processes not exceeded 20%.
How can i understood my CPU performance from the above values.

By: Tony

Tony — Wed, 08 Sep 2010 22:04:28 +0000

The average CPU usage is:

(103568-102843 + 0-0 + 67109-66548)/(4345597-4308888)
=0.0350322809

only 3.5%, but the estimation is not accurate

By: Tony

Tony — Wed, 08 Sep 2010 22:01:49 +0000

You can try to use /proc/stat to calculate CPU utilization.

If the information is displayed like this:
cpu 607557 143290 385125 136873807 1279793 18764 14856 0 0

To get the average system load over any given amount of time you read only the first four values into variable (for example, ill call them u1, n1, s1, and i1). Then when you’re ready you read the values again into new variables, u2, n2, s2, and i2. Now your total usage time is equal to (u2-u1) + (n2 – n1) + (s2 – s1). And your total time overall is the usage time + (i2-i1). Take (100*usage)/total and you have your percent CPU Usage.

By: Rey

Rey — Fri, 23 Jul 2010 14:45:21 +0000

Is there anyway to determine CPU cycles currently in use and available CPU Cycles.