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Split the sigmakin kernel into smaller kernels #310
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This is just a placeholder to discuss the idea of implementing smaller kernels.
A lot of pointers already exist related to this:
- Stefan's WIP PR WIP - Split kernels and more #242
- issue cuda graphs #12 about cuda graphs
- issue Cuda streams #11 about cuda streams
- issue "xxx" function interface: further separation of data access and calculations? #175 about the internal APIs
One of the main points towards using smaller kernels is the need to allow each ixx/oxxx and each ffv function to handle pointers to large buffers for many events and to do the indexing themselves. This is discussed in #175 (comment) for instance. Presently instead only the ixx/oxx functions are able to find an event in the input array, but then their output (and all inputs/outputs of the ffv functions) refer for CUDA to a single event. This is the first thing that must be changed to allow smaller kernels.
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valassi commentedon Dec 11, 2021
Note a basic prototype idea in #313: it would be enough to add for instance bufferAccessWavefunction( fptype* buffer, int iw6 ) wherethe iw6 index is passed in the same way as the ip4 now.
valassi commentedon Jan 20, 2022
Note that PR #328 is the first step for this and contains several comments related to this
valassi commentedon Feb 3, 2022
The color algebra optimisation has a separate issue #155. Improving the timing measurements is in #372.
valassi commentedon Apr 22, 2022
One of the main issues in splitting kernels is the clarification of the relative roles of MEK and CPPProcess: who holds intermediate data buffers? who orchestrates the order of kernels? who is allowed to have process specific stuff? I am discussing this largely in #356, specifically in the econtxt of running alphas issue #373 and draft PR #434
valassi commentedon Nov 23, 2025
Kernel splitting is implemented in PR #1049 (merged) and PR #1066.
Full documentation in https://arxiv.org/abs/2510.05392v2 that should appear tomorrow