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Determining number of processors in a virtualized system

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Neal Eckhardt

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Jan 8, 2009, 2:01:12 PM1/8/09
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We have an LPAR defined to use .6 processors. The number of processors
assigned to the LPAR had a DESIRED value of 3. We tried to run a
software package licensed for 2 CPUs, and it failed since it detected
3 CPUs.

1. How does software determine the number of CPUs available?

2. Is there an AIX command that will display the number of CPUs it
thinks it has?

The desired CPUs was changed to 2 in the HMC, but the package still
sees 3 CPUs. Are there additional steps required to get the software
in AIX to see the lower number of logical CPUs?

The hardware is a 570.

Thanks,
Neal

--
Neal

Being stubborn is a virtue when you’re right - it’s only
a character flaw when you’re wrong.

Jan van Beers

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Jan 8, 2009, 2:40:52 PM1/8/09
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Neal Eckhardt <neck...@penntraffic.nospam.com> wrote:
>We have an LPAR defined to use .6 processors. The number of processors
>assigned to the LPAR had a DESIRED value of 3. We tried to run a
>software package licensed for 2 CPUs, and it failed since it detected
>3 CPUs.
>
>1. How does software determine the number of CPUs available?
>
>2. Is there an AIX command that will display the number of CPUs it
>thinks it has?

lscfg will report the number of processors.

>The desired CPUs was changed to 2 in the HMC, but the package still
>sees 3 CPUs. Are there additional steps required to get the software
>in AIX to see the lower number of logical CPUs?

Did you change the profile or did you reconfigure dynamically?

>Thanks,
>Neal
Cu
Jan
--
wings and claws

Neal Eckhardt

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Jan 8, 2009, 4:13:47 PM1/8/09
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Thanks for getting back to me Jan.

It turns out the guy did not do the dynamic reconfiguration, he just
changed the permanent definition (that I guess would have taken effect
after AIX is rebooted).

We found the dynamic configuration, and it worked perfectly. Between 3
of us we figured it out ;)

Working with this stuff with no education is a wonderful thing.

Thomas Braunbeck

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Jan 9, 2009, 12:37:23 AM1/9/09
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Neal Eckhardt schrieb:

>
> It turns out the guy did not do the dynamic reconfiguration, he just
> changed the permanent definition (that I guess would have taken effect
> after AIX is rebooted).
>

I think rebooting the OS is not enough here (reboot, shutdown -Fr).
Why should the HW config change on a simple OS reboot? You must
power off (LPAR HW resources are returned to the hypervisor)/on
(hypervisor assigns HW resources as defined in the profile to the
LPAR). So shutdown (-F), when LPAR power is off, power on.

Mark Taylor

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Jan 9, 2009, 4:38:10 AM1/9/09
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lparstat -i will give you the info you need. lscfg will report the
number of virtual cpus online, this is not the same as physical cpus
or logical cpus as you can carve up each cpu to a min of 0.1 and
increments of 0.01, so you may want to check the licensing model for
the app you are installing .. oracle for example gets licensed on the
whole frame i.e. for all the physical cpus, so you can carve the
system up how you like. other apps will differ.

Check out the PowerVM redbooks.

HTH
Mark Taylor

Gary R. Hook

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Jan 9, 2009, 9:11:38 AM1/9/09
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Thomas Braunbeck wrote:
> Neal Eckhardt schrieb:
>
>>
>> It turns out the guy did not do the dynamic reconfiguration, he just
>> changed the permanent definition (that I guess would have taken effect
>> after AIX is rebooted).
>>
> I think rebooting the OS is not enough here (reboot, shutdown -Fr).

Correct. You must power the partition down, then back up to put
a new profile in effect.

--
Gary R. Hook
________________________________________________________________________
Vocatus atque non vocatus deus aderit

Gary R. Hook

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Jan 9, 2009, 9:13:45 AM1/9/09
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Look at the _system_configuration structure in sys/systemcfg.h to
see how software can get info about the system resources.

Neal Eckhardt

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Jan 12, 2009, 9:31:28 AM1/12/09
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On Fri, 09 Jan 2009 08:13:45 -0600, "Gary R. Hook"
<obfu...@nospam.net> wrote:

>Mark Taylor wrote:
>> lparstat -i will give you the info you need. lscfg will report the
>> number of virtual cpus online, this is not the same as physical cpus
>> or logical cpus as you can carve up each cpu to a min of 0.1 and
>> increments of 0.01, so you may want to check the licensing model for
>> the app you are installing .. oracle for example gets licensed on the
>> whole frame i.e. for all the physical cpus, so you can carve the
>> system up how you like. other apps will differ.
>
>Look at the _system_configuration structure in sys/systemcfg.h to
>see how software can get info about the system resources.

Thanks Gary, I looked up that header file, and it explained all.

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