Oracle has changed its pricing for software running on multi-core processors.

Unlike others, Oracle plans to continue pricing its products per processor core rather than per socket, but will use different multipliers for different types of chips to decide how many software licences a company needs to buy.

Pricing for software run on servers with Intel/AMD chips will be determined by multiplying the number of processor cores in a server by 0.5, Oracle said. Therefore, an Oracle database running on HP's DL585 with four dual-core AMD Opteron processors would require four licences (eight cores multiplied by 0.5).

Sun's new T1 processor, formerly Niagara, comes with a 0.25 multiplier. Niagara processors have up to eight separate processor cores, with each core capable of processing four threads. New servers with the chip have only one processor, but the eight-core version of the processor will only require two licences, Oracle said.

All other multi-core chips, such as Sun's UltraSparc IV+ or IBM's Power, will keep the 0.75 multiplier first announced by Oracle in July. Single-core processors have a multiplier of 1.0.

Software companies have rethought their processor licensing models this year as multi-core processors have become much more common. Customers had been worried their licensing costs would double if software companies charged them per processing core, rather than per socket, to run the same software on new servers with dual-core chips.

But Microsoft and IBM decided earlier this year to treat dual-core x86 processors such as AMD's Opteron or Intel's Xeon as one processor. IBM considers its own dual-core Power processors to be two chips for licensing purposes.