[petsc-dev] ASM for each field solve on GPUs

Jed Brown jed at jedbrown.org
Thu Dec 31 16:23:08 CST 2020

Stefano Zampini <stefano.zampini at gmail.com> writes:

> You should swap fieldsplit and ASM
> -pc_type fieldsplit
> -fieldsplit_0_pc_type asm

Note that this incurs separate communication for each split. If you nest them the other way, there would be one heavy communication and then a bunch of local work. This latency impact may not matter as much when you're already launching GPU kernels for the local work, though the communication to/from device memory is also expensive. 

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