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kernel idle

Frequent Advisor

kernel idle

Hi admis,
trucluster 5.1A,pk1
the output top command is:
PID USERNAME PRI NICE SIZE RES STATE TIME CPU COMMAND
1073233 oracle 42 0 3795M 58M sleep 359:07 27.70% oracle
1048576 root 0 0 13G 383M run 302:32 24.60% kernel idle
1387921 oracle 42 0 3741M 4349K sleep 38:09 22.00% oracle
1406870 sytliv 42 0 9616K 712K sleep 0:00 20.00% sftp-server2
1405997 oracle 42 0 3740M 3383K sleep 0:55 16.60% oracle
1398822 oracle 42 0 3744M 7118K sleep 1:20 10.80% oracle
1406837 oracle 46 0 3739M 2105K sleep 0:00 10.80% oracle
1381713 oracle 45 0 3741M 4341K sleep 5:10 9.80% oracle
1394923 oracle 42 0 3741M 4390K sleep 2:59 9.70% oracle
1388419 oracle 42 0 3742M 5226K sleep 0:42 8.20% oracle
1406533 root 45 0 9208K 6103K run 0:02 7.60% top
1405137 oracle 45 0 3741M 4431K run 0:28 7.50% oracle
1400334 oracle 42 0 3743M 5873K sleep 0:19 7.00% oracle

please advise why the kernel idle proccess
consume more cpu tile 24.60%
thanks.

5 REPLIES
Honored Contributor

Re: kernel idle

I think that is because there are not many processes that are ready to run (many are sleeping)
Esteemed Contributor

Re: kernel idle

jousif,

Is your cluster set up as a NFS server? If so, are you using TCP protocol instead of UDP? This may be the problem as was in this case:

http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=769502

Also, here's a link to a good description for what kernel idle is used for:

http://unix.derkeiler.com/Mailing-Lists/Tru64-UNIX-Managers/2004-09/0024.html

Vic
There are 10 kinds of people, one that understands binary and one that doesn't.
Honored Contributor

Re: kernel idle

Iousif,

Here is the thread which discusses about CPU's idle time...
http://groups.google.com/group/fa.alpha-osf-managers/browse_frm/thread/2fbabd2daf9b42dc/c484bfd14115f8ea?lnk=st&q=Tru64+cpu+idle+time&rnum=2&hl=en#c484bfd14115f8ea


Archunan

God is Artist, we are all just brushes
Honored Contributor

Re: kernel idle

Iousif,

we can find processor-wise CPU idle time details using monitor and collect commands.

And there is a example program cpustat which displays time in each node/cpu.

Archunan

God is Artist, we are all just brushes
Esteemed Contributor

Re: kernel idle

Hm. One of those pointers are to what I wrote before.

In this case I would just say: if you don't trust the CPU time on the system used by the kernel, run kprofile. If you see a lot of time in locking, use lockinfo. If you don't have a lot of system time, the system is probably just idle (but kprofile should show that).

The release you're running is quite old. Around that time frame there was a problem when CPU time was not always attributed to "kernel idle" correct. Just a cosmetic problem.
//Add this to "OnDomLoad" event