PetscParallelSortInt#

Globally sort a distributed array of integers

Synopsis#

#include "petscis.h" 
PetscErrorCode PetscParallelSortInt(PetscLayout mapin, PetscLayout mapout, PetscInt keysin[], PetscInt keysout[])

Collective

Input Parameters#

mapin - PetscLayout describing the distribution of the input keys
mapout - PetscLayout describing the desired distribution of the output keys
keysin - the pre-sorted array of integers

Output Parameter#

keysout - the array in which the sorted integers will be stored. If mapin == mapout, then keysin may be equal to keysout.

Notes#

This implements a distributed samplesort, which, with local array sizes n_in and n_out, global size N, and global number of MPI processes P, does:

  - sorts locally
  - chooses pivots by sorting (in parallel) (P-1) pivot suggestions from each process using bitonic sort and allgathering a subset of (P-1) of those
  - using to the pivots to repartition the keys by all-to-all exchange
  - sorting the repartitioned keys locally (the array is now globally sorted, but does not match the mapout layout)
  - redistributing to match the mapout layout

If keysin != keysout, then keysin will not be changed during PetscParallelSortInt().

Level#

developer

Location#

src/vec/is/utils/psort.c

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