cholla-hydro/cholla

CPU_TIME reduction

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#328 opened on Sep 7, 2023

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enhancementhelp wanted

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Description

Currently the time reduction uses MPI_Allreduce simply because some reduction routines already existed in mpi_routines.h

This performs an extra unnecessary step of sending the result back out to all procs, but I believe only proc 0 needs the reduced data. MPI_Reduce should suffice.

Contributor guide

Research direction
Examine mpi routines.h to find the MPI Allreduce call for CPU TIME, then change it to MPI Reduce so that only root process (proc 0) receives the reduced value, adjusting subsequent usage accordingly.
Tech stack
ccpp
Domain
performancehpc
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
1
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++MPI
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60