Classification of OOC Problems

The models for OOC computation provide abstractions with which a runtime system or a compiler does not have to deal with machine specific features and low-level APIs. The three most common execution models are described below .

• In the global placement model a file is stored on a single virtual disk and is shared between all processors.

• In the local placement model, the out-of-core local array of each processor is stored in separate logical file. A file owed by some other processor cannot be explicitly accessed and requires communication with the owner that performs IO operations.

• in the partitioned in-core model the global data array is logically divided into a number of partitions each of which can fit in the combined main memory of the processors. Thus computation on each partition is primarily an in-core problem and no I/O is required during the computation of the partition.

Additionally, irregular OOC problems can be divided with respect to the type of arrays which are OOC .

• out-of-core index and in-core data arrays; usually the size of indirectional arrays is greater than that of corresponding data arrays . In some cases, data arrays are small enough to be kept in the main memory.
• out-of-core index and data arrays; In the general version of OOC problems there is an assumption that both types of arrays are out-of-core.

Created by Katarzyna Zając