Fun:/home/test>lparstat 2 100
System configuration: type=Shared mode=Uncapped smt=On lcpu=8 mem=17408 psize=20 ent=0.40
%user %sys %wait %idle physc %entc lbusy vcsw phint
54.4 28.2 9.5 7.9 1.30 324.5 21.4 8766 336
57.3 26.5 11.3 4.9 1.36 340.6 24.3 8773 367
Does this mean we need to add more resources here? If yes, what needs to be added? Thanks in advance.
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4 replies Latest Post - 2012-04-06T14:24:39Z by seroyer
Pinned topic Resource Addition Required?
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Updated on 2012-04-06T14:24:39Z at 2012-04-06T14:24:39Z by seroyer
SystemAdmin 110000D4XK1744 PostsACCEPTED ANSWER
Re: Resource Addition Required?2012-04-05T16:57:01Z in response to atifmunirHi,
During this workload, you are using 1.30 physc, so more than your 0.4 entitled capacity.
As you are uncapped, the capacity needed above your EC is shared by all uncapped lpar in the Shared Processor Pool (SPP).
So if all lpar need more cpu than their EC and the SPP is overloaded, the hypervisor will dispatch the shared capacity to all LPAR on a weight basis.
So it depends if you are in production, if your lpar is always loaded like this...
JackTommy 27000577QN9 Posts
bassemir 110000CMX989 PostsACCEPTED ANSWER
Re: Resource Addition Required?2012-04-06T13:37:31Z in response to JackTommyThis is just my opinion... if the LPAR is always using more than it is entitled to use (ent > 100%) then I would increase entitlement to the the lowest usage.
For example if I never seen the ent drop below 200% I would change ent from 0.4 to 0.8. This way I know the LPAR is entitled to the minimum cpu resources it needs to run its workload.
The reason I would not set ent higher is because if I were to do that than I would be taking CPU resources out of the shared pool for this partition that sometimes would not be needed. Thus reducing my ability to make the full use of all my cpu resources.
For example if I set ent=1.2, there would be times when 0.4 of the reserved cpu resources are not being used by my LPAR and not in the shared pool. I don't believe the hypervisor would take away cpu resources below the LPAR's entitlement for another LPAR.
Another side of me thinks, just leave ent=0.4 and let the system manage the cpu resources as it was designed and don't worry about it. When workload peaks and you need 3.2 physical cpus (800% of entitlement)let the hypervisor give the LPAR the needed resources.
Like others have side, "it depends" on what you want to do and prioritize the cpu resources between the LPARs. This technology is pretty cool and very flexible.
seroyer 120000AD3Y352 PostsACCEPTED ANSWER
Re: Resource Addition Required?2012-04-06T14:24:39Z in response to bassemirYes, I do think it is a good idea to set the entitled capacity to a reasonable value for your workload, so that typical utilization is near 100%, as opposed to letting the utilization typically run much higher, like 500%.
However, the hypervisor does make unused capacity available to other uncapped partitions. So, if LPAR A's entitled capacity is 2.0 processing units, but it is currently only utilizing 1.2 processing units, the extra 0.8 processing units worth of capacity are available to other uncapped partitions if they can use it.
The entitled capacity value ensures that, if the partition can use all of its entitled capacity, the hypervisor will give it those cycles. If the partition does not need all of that capacity, those cycles are available to other uncapped partitions.