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Only half CPUs being fully utilized

 
Kenneth Penland
Frequent Advisor

Re: Only half CPUs being fully utilized

came back from lunch and it is no longer "in the red" so to speak, but looking at top you can still see that 1-4 are favored (see attached)

I even looked at psrset and it looks like all cpus are just in the default grouping:

$ /usr/sbin/psrset
PSET 0
SPU_LIST 0 1 2 3 4 5 6 7
OWNID 0
GRPID 0
PERM 755
IOINTR ALLOW
NONEMPTY DFLTPSET
EMPTY FAIL
LASTSPU DFLTPSET
LDOM_LIST 0 1
RTE DISALLOW
djoshi
Frequent Advisor

Re: Only half CPUs being fully utilized

Hi,

My opinion, if the database is running slow, it does not mean that problem with the UNIX system. My advice check the database logs as well.

If your system having 8 CPU, it does not mean all 8 will be busy every time, it depends on the incoming request and load.

This is what I can think as of now.
Elmar P. Kolkman
Honored Contributor

Re: Only half CPUs being fully utilized

What kind of storage are you using for your database?
SYS could also mean the system is really busy providing the data for the database, blocking almost all I/O for other processes on the filesystem but showing 'activity' in top. (Glance does this better, especially when zooming in on processes or looking at syscalls.)
Every problem has at least one solution. Only some solutions are harder to find.
Ganesh Balraman
Regular Advisor

Re: Only half CPUs being fully utilized

Hi Penland!

Could you provide some more details.

parstatus -V
vparstatus -V (if vpar exist)
sar -Muqc
sar -b
sar -v
sar -u
ioscan | grep -i processor
uname -r


Best Regds,
Ganesh
Kuntal Gupta
Frequent Advisor

Re: Only half CPUs being fully utilized

I think you are using SIM where 4 cores are assigned by any policy.
To confirm whether SIM is running use
#ps -eaf | grep -i wbem

If yes, login to SIM by http://:280 to confirm
Bill Hassell
Honored Contributor

Re: Only half CPUs being fully utilized

> only 4 are getting hit hard...

This means that only 4 processes are busy computing and the rest are either sleeping or waiting on I/O. You can't expect a single process to be split across multiple CPUs. Your DBA configures the number of available processors in Oracle and Oracle with adjust internal code to take advantage of the resources. But for a single thread of code, only one CPU will be used. If it uses 100% of that CPU, you cannot 'share' the load across 2 CPUs.


Bill Hassell, sysadmin
Kenneth Penland
Frequent Advisor

Re: Only half CPUs being fully utilized

thanks all for your responses...currently the system is down....my fingers are crossed that once it comes back up it will be on something OTHER than 1-4 ;)
chris huys_4
Honored Contributor

Re: Only half CPUs being fully utilized

Hi Kenneth,

Your second top output, shows that also cpu 6 gets hammered, so I dont think the problem is the # of cpu "an sich".

However its not normal that oracle processes are spending that much time in 'system mode'.

Log a call with oracle support and see if they can find out which system calls are causing the oracle processes to spend that much time in system mode.

If oracle support doesnt come up with satisfying answers, log a performance case with hp support and a internal tool as kitrace should be able to find out what is going on.

Greetz,
Chris
PS. Installing the latest patchbundle should also be a good idea.
Kenneth Penland
Frequent Advisor

Re: Only half CPUs being fully utilized

thanks, I shared your thoughts with the DBAs to see what they say....on a side note..the box was rebooted a few days ago and when everything was restarted cpus 1-4 took the top spots again, leaving the rest of the CPUs idle in comparison. I was hoping 4 new CPUs would be maxed out but it was the exact same ones as before...we have a call out to the next level of HP support to try and figure it out.
Mark H Stewart
Frequent Visitor

Re: Only half CPUs being fully utilized

Kenneth, I did a Google search on those Oracle process names, and didn't find any hits; I'm curious what they are.

I have a somewhat similar situation, but in my case, it is when I invoke the PL/SQL package dbms_stats.gather_table_stats with the degree parameter specifying parallel processing. Oracle proceeds to launch 72 processes, but they only run on 4 of the 8 CPUs. I enabled hyperthreading, and same results: the processes only run on 8 of the 16 CPUs! I've had installed the Oracle-recommended patches for 11.31, and same results. I have a ticket open with Oracle. I can do other queries that do use all the CPUs, but that particular command is using just half the CPUs.
Chance favors the prepared mind. - Louis Pasteur