GPU memory estimation

HTTomo uses GPU memory estimators to determine how many data slices can be processed at once. This defines the size of the blocks used within each section.

Fig. 24 HTTomo selects a safe block size that satisfies the memory requirements of every method in a section.

Selecting a block size

HTTomo first determines the available memory on the selected GPU. For a candidate block size, each GPU method in the section estimates its peak memory use, including its inputs, outputs and temporary allocations.

The most memory-demanding method limits the block size. HTTomo selects a block that fits the available memory for every method, then uses that size throughout the section. Iterative estimators may return a safe near-maximum value rather than the exact largest possible block.

Why block size matters

Larger blocks use the GPU more efficiently and reduce the number of data transfers and method calls. The memory estimators maximise block size while preventing out-of-memory failures.

Memory requirements vary between methods and may depend on the data shape, data type and method parameters. See Memory estimation and block sizing for details about implementing and testing GPU memory estimators.