petsc-3.14.6 2021-03-30

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 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 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
Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages