AIX

Hi All,

It may be a n00b question, but i really want to know , How Entitled Capacity is less and Used CPU is more when there is no Free CPU is available in the managed system.

I have 5LPARs in a MS with Dual VIO.
Managed System CPU details
Available: 0.20
Assigned to partitions: 15.80
Configurable: 16.00

LPAR Details
Node1- 4.4 Entitled Capacity - Capped

Node2- 4.4 Entitled Capacity - Capped

Node3- 2 Entitled Capacity - Capped

Node4- 1 Entitled Capacity - Capped

Node5- 2 Entitled Capacity - UnCapped - Processor Used is 5 !!!

VIO 1 - 1 Entitled Capacity - UnCapped

VIO 2 - 1 Entitled Capacity - UnCapped

While analyzing NMON report of Node5 - the CPU used is 5.

How is this possible when no CPU is available?

I'm sure i got stuck up in some concept.


Thanks,
Sharath

You need to also list how many Virtual CPUs an LPAR has to understand this.

If an LPAR doesn't use it's entitled capacity is donates it back to the pool and can be allocated to other LPARs based on need and weighting. so although it's entitlement may be quite low, the server finds and reallocates unused processor time, so the situation you describe is very common.

The best way - In my opinion - to see what the CPU on an LPAR is doing is to use the

Code:

vmstat 1

command and look at the ent% column as this shows how much CPU the LPAR is using relative to the entitled capacity.

Entitled Capacity means that the LPAR is guaranteed to have that amount of CPU available to it, and that is what the Assigned to Partitions number means, is the sum of all entitled capacities for LPARs in the server.

Hope That helps
Ross

Thanks for your reply,

I accept your statement, but is it possible if the LPAR is capped and it could share its free cpu to other Lpars in the same Managed System?

Kindly explain, im lagging

As ross.mather has said, if your entitled capacity is not used, it goes back into the resource pool. If your LPAR CPU entitlement is capped, it obviously won't share it. What's there to share if its capped?

Ur right! but here all the LPARS are capped then from where did i got the 3CPU extra used for Node5?

Node5
--------
2Entitled Capacity + ? = 5Used cpu

Although VIOs are uncapped but each has only 1CPU so it cant be the reason!!

I don't know where you are getting your information from about what is entitled and what's used etc.
Perhaps go on your HMC and show me the LPAR profile set up you have done.
Read on lssyscfg for more information.

First off, i 'd like to ask you to kindly refrain from using leet-speak around here. I am sure it will enhance your chances of getting an answer if you undergo the effort to write "you are" ("you're") instead of "ur". After all, we are professionals here and we talk that way. Thank you for your consideration.

Yes, your LPARs are capped, but that does not mean they can't give back to the pool the resources they do not need at the moment. "Capped" only means that they cannot allocate needed resources above a certain point (the "maximum" value). So, if your other LPARs are more or less idle and your LPAR Nr. 5 is very busy it could allocate additional processors released to the pool from the other LPARs. If they would start to need their resources themselves of course the LPAR 5 owuld have to give them back.

I hope this helps.

bakunin