[SYSTEMDS-209] Performance sparse matrix-colvector cell-wise multiply

While working on the new builtin function for connected components and
ultra-sparse graphs, we found that 'rowMaxs(G * t(c))' performed orders
of magnitude better than the semantically equivalent 't(colMaxs(G *
c))'. The reason was a missing handling of strict sparse-safe operations
for matrix-colvector operations, while this was already handled for
matrix-rowvector operations. In detail, we performed unnecessary
operations in the number of cells instead of in the number of non-zeros
leading to worse asymptotic behavior.

With the simple fix of this patch, now we have very similar performance.
For example, on a scenario of performing 100 times G*c where X is a
10Kx10K, sparsity=0.0001 matrix, total execution time (for 100
operations) improved from 4.2s to 167ms.
2 files changed
tree: a0a222dfa528eaa9803d21603ad1c695ec23e5e8
  1. .github/
  2. bin/
  3. conf/
  4. dev/
  5. docker/
  6. docs/
  7. scripts/
  8. src/
  9. .gitattributes
  10. .gitignore
  11. CONTRIBUTING.md
  12. LICENSE
  13. NOTICE
  14. pom.xml
  15. README.md
README.md

Apache SystemDS

Overview: SystemDS is a versatile system for the end-to-end data science lifecycle from data integration, cleaning, and feature engineering, over efficient, local and distributed ML model training, to deployment and serving. To this end, we aim to provide a stack of declarative languages with R-like syntax for (1) the different tasks of the data-science lifecycle, and (2) users with different expertise. These high-level scripts are compiled into hybrid execution plans of local, in-memory CPU and GPU operations, as well as distributed operations on Apache Spark. In contrast to existing systems - that either provide homogeneous tensors or 2D Datasets - and in order to serve the entire data science lifecycle, the underlying data model are DataTensors, i.e., tensors (multi-dimensional arrays) whose first dimension may have a heterogeneous and nested schema.

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Status and Build: SystemDS is still in pre-alpha status. The original code base was forked from Apache SystemML 1.2 in September 2018. We will continue to support linear algebra programs over matrices, while replacing the underlying data model and compiler, as well as substantially extending the supported functionalities. Until the first release, you can build your own snapshot via Apache Maven: mvn clean package -P distribution.

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