Cores vs. Processors vs. PVUs? What the heck?!


Cores vs. Processors

In the rapidly changing world of technology, old words may take on new meanings. Following are four key definitions that all IBM software sellers and consumers need to understand in order to fully explain IBM’s software licensing to customers:

·         Core – A functional unit within a computing device that interprets and executes software instructions.

·         Chip – electronic circuitry, containing but not limited to at least one core, on a silicon wafer.

·         Socket – the mount that secures a chip to a motherboard.

·         Processor – There is currently disagreement in the computer industry over the definition of a processor. IBM defines a processor as the core. For example, a dual-core chip has two processor cores on it.

IBM, as do most middleware vendors, continue to define a processor as the core because this is where the software actually executes. Most hardware vendors, though now define the processor as a chip. This change began with the introduction of x86 dual-core chips in April, 2005.

Some people in the industry, especially hardware vendors, have suggested this point of customer confusion could be solved if middleware were licensed at the chip level instead of the core. This approach won’t satisfy customer requirements, though. With the power available in today’s processor cores, customers increasingly want to partition their systems so that an application runs in a subset of the processors in a server, and have the licensing structure support this. This is the reason IBM introduced sub-capacity licensing in April, 2005.

For an example, let’s look at a customer who has a server with two dual-core chips (4 processor cores) and only wants to run WebSphere Portal on one core. If per chip licensing were used, they would effectively have to license for both processor cores on that chip, not just the one the customer was actually running the middleware on. Leveraging sub-capacity licensing at the processor core level, however, they would only require WebSphere Portal to license at that level. This situation will worsen as the number of cores per chip continues to increase in the coming years.

Processor Value Unit Licensing

IBM is addressing the processor vs. core issues by introducing the per processor licensing replacement, processor value unit licensing. A processor value unit is simply a unit of measure used to differentiate licensing of middleware on processors and, over time, will evolve to differentiate processor families based on their relative performance. Initially, however, our focus is on converting customers to processor value units without changing customer prices for IBM middleware deployed on existing processors.

Going forward, IBM middleware, formerly licensed using the per processor metric will now be licensed in processor value units. We have converted the 3 broad tiers or levels in the prior structure and all existing processors have been assigned to one of those tiers. For each product, customers will need to acquire the appropriate number of processor value units for the level or tier of the specific processor on which the software is deployed.

IBM Software defines a processor as a core:

Chip type

Number of cores

Value units  per core

Single core (all platforms)




RISC Dual-core




Itanium Dual-core




x86 Quad-core or Dual-core

4 or 2



PowerPC 970 Dual-core




Power 5 Quad-core Module (QCM)




Sun T1* Octi-core, Hexa-core, or Quad-core 

8, 6, or 4



* T1 entitlements per processor adjusted with the elimination of fractional licenses.

Figure 6: Processor Value Units per CPU Type

To convert existing per processor licenses to the new processor value unit licenses, we have used a conversion factor of 100. As an example, each core on an x86 dual-core based system required one half of one license entitlement before this announcement.  To convert this to processor value units, you would multiply the 0.5 per processor license by the conversion factor of 100 to get the new processor value unit requirement of 50.

So who do I calculate PVUs needed?  Fortunately there’s this thing called a Processor Value Calculator.  Give it a try.

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