search

dash-project / dash

DASH, the C++ Template Library for Distributed Data Structures with Support for Hierarchical Locality for HPC and Data-Driven Science
http://www.dash-project.org/
Other
154 stars 44 forks source link

Change distribution after create Matrix #698

Open Goon83 opened 4 years ago

Goon83 commented 4 years ago

Hi All, Another question regarding the function availability of DASH.

What will happen if I change the distribution (block size, halo layer) of a existing Matrix ? Will the DASH support re-distribution the data following new parameters?

Bests, Bin

devreal commented 4 years ago

What will happen if I change the distribution (block size, halo layer) of a existing Matrix ? Will the DASH support re-distribution the data following new parameters?

I'm not sure that is possible with the current interface. Once a matrix is allocated there is no way to change its layout (afaics).

Goon83 commented 4 years ago

Hi @devreal Got it and thanks for the clarification.

Bests, Bin

devreal commented 4 years ago

Could you elaborate what you have in mind for it? Maybe we will get a chance at some point to implement such a feature if there is a good use case.

Goon83 commented 4 years ago

Hi @devreal It is like the "repart" operator in SciDB (doc). . The "repart" changes the chunk size (called tile size in DASH) of an existing array. The "repart" in SciDB mostly involves the disk operation (might be just metadata but not sure so far). A "repart" for DASH array definitely needs to consider lots of communication among processes (units in DASH) to redistribute data.

We might also explore this idea in near future. To avoid repeating work, ping me DBin@lbl.gov if you are interested in working together. We can have a chat then.

Bests, Bin

fuchsto commented 4 years ago

@dash-project/developers First, I want to announce my "comeback" as an active contributor to DASH after my hiatus of over a year. Regarding this feature request, I have prepared concepts for dynamic adaptations such as load-balancing dash::Matrix (aka dash::NArray) which I originally designed. Also, I'm currently supervising a master's thesis on sparse matrix concepts for DASH. I will put the respective current states of development in feature branches as soon as possible.

In brief, the NArray / Matrix concepts will not be affected but extended by additional free-function-style concepts. So if you (@Goon83) can use dash::Matrix in its current state and postpone the rebalancing / repartitioning parts in your work, your existing code will be unaffected.

Goon83 commented 4 years ago

Hi @fuchsto Sorry for not monitoring this thread closely.

Welcome back to this wonderful project.

Yes, the rebalancing feature is very interesting to us.

Let me know how can I help. Bests, Bin