Help answer threads with 0 replies.
Go Back > Forums > Other *NIX Forums > AIX
User Name
AIX This forum is for the discussion of IBM AIX.
eserver and other IBM related questions are also on topic.


  Search this Thread
Old 04-28-2004, 08:14 AM   #1
LQ Newbie
Registered: Apr 2004
Posts: 8

Rep: Reputation: 0
kernel takes a lot of CPU


When I do a "topas" on my AIX server, it shows that my kernel takes 60%, users 40%, wait 0% and Idle 0%.
Is it good/right ?
How can I see what my kernel does ?
ps -ef gives me users informations, but what about the kernel ?


PS: excuse me for my english ...
Old 04-28-2004, 09:18 AM   #2
Registered: Nov 2002
Location: England
Distribution: Ubuntu 9.04
Posts: 631

Rep: Reputation: 30
Most processes have kernel and user components. "Kernel" CPU is when the kernel is doing something (e.g. making system calls, talking to devices, checking permissions), "User" is when the process is doing something on its own without the kernel being involved.

The figures you have look OK. The balance between kernel and user components will depend on the individual applications and what you are doing with them.

However, the rule of thumb is that you add together kernel and user to get the total CPU%. In your case, the total CPU% is 100 which means you are CPU-bound : this might be OK for batch jobs, but will be hurting performance for any interactive work.

Look at the top CPU-hogging processes (ps aux sorts processes by CPU use).
Old 04-28-2004, 01:46 PM   #3
Registered: Feb 2004
Location: Paris
Posts: 398

Rep: Reputation: 31
Of course, this means that you are using all of your cpu power. 60-40 is a good ratio.
If is the cause from time to time, don't panic.
If this occurs 24 hiours per day, and if you find it not comfortable, you should consider buying extra cpu's if you have a multi-cpu upgradable machine.
Old 04-29-2004, 08:41 AM   #4
Mark Taylor
Registered: Apr 2004
Posts: 60

Rep: Reputation: 15
err... no, this is not good .... looks like your system is cpu bound.

usr + sys constantly above 80% = cpu bound

You need to work out what kernel task is spinning, you could be hitting one of many kernel routine spin defects.

what level of code are you running ? what ML levels ?

run tprof / pprof to work out what is using the most cpu ticks and post the offending routine / proc / system call then i should be able to teel you if its a known defect or not...... could be that you just need more cpu power, but you want to rule out the cheapest options 1st like APARs.

Mark Taylor


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
XORG using a lot of CPU resources GreatBrak Ubuntu 1 12-02-2005 02:56 PM
Midnight Commander takes a lot of time starting julot Linux - Software 3 07-26-2005 08:20 PM
FC 2 GNOME takes 99.9% of cpu. bruse Fedora 6 04-26-2005 07:24 PM
not using swap / kjournald using a lot of CPU bhatcher Linux - General 3 02-18-2004 10:28 PM
Linux (with KDE+GNOME) takes a lot of RAM! ajagodnik Linux - General 12 12-28-2003 09:57 AM > Forums > Other *NIX Forums > AIX

All times are GMT -5. The time now is 12:33 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration