tree b6f2a61436a50f117f0e0faee9127fce86e4e662
parent ba65ddd311239c26dd8950ab37f504d37bf6fa44
author Sameer Agarwal <sameeragarwal@google.com> 1661423534 +0530
committer Sameer Agarwal <sameeragarwal@google.com> 1661732668 -0700

Optimize  the BlockCRSJacobiPreconditioner

Instead of iterating row-wise, use the row block structure
to update the preconditioner one row block at a time.

While benchmarking, I also found an opportunity to speed up
BlockSparseJacobiPreconditiner.

Before
-----------------------------------------------------------------------------------------
Benchmark                                               Time             CPU   Iterations
-----------------------------------------------------------------------------------------
BM_BlockSparseJacobiPreconditioner              132122392 ns    132103000 ns            5
BM_BlockCRSJacobiPreconditionerBA                73365217 ns     73335800 ns           10
BM_BlockSparseJacobiPreconditionerUnstructured   92407762 ns     92407714 ns            7
BM_BlockCRSJacobiPreconditionerUnstructured      72256367 ns     72256400 ns           10

After

-----------------------------------------------------------------------------------------
Benchmark                                               Time             CPU   Iterations
-----------------------------------------------------------------------------------------
BM_BlockSparseJacobiPreconditionerBA             39723456 ns     39722222 ns           18
BM_BlockCRSJacobiPreconditionerBA                46561625 ns     46561667 ns           15
BM_BlockSparseJacobiPreconditionerUnstructured   52676208 ns     52676167 ns           12
BM_BlockCRSJacobiPreconditionerUnstructured      54430564 ns     54421462 ns           13

Change-Id: I6da8e044b26f0c24481deee5722322a606e9e5ca