furnace/extern/fftw/mpi/block.c

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/*
* Copyright (c) 2003, 2007-14 Matteo Frigo
* Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include "ifftw-mpi.h"
INT XM(num_blocks)(INT n, INT block)
{
return (n + block - 1) / block;
}
int XM(num_blocks_ok)(INT n, INT block, MPI_Comm comm)
{
int n_pes;
MPI_Comm_size(comm, &n_pes);
return n_pes >= XM(num_blocks)(n, block);
}
/* Pick a default block size for dividing a problem of size n among
n_pes processes. Divide as equally as possible, while minimizing
the maximum block size among the processes as well as the number of
processes with nonzero blocks. */
INT XM(default_block)(INT n, int n_pes)
{
return ((n + n_pes - 1) / n_pes);
}
/* For a given block size and dimension n, compute the block size
on the given process. */
INT XM(block)(INT n, INT block, int which_block)
{
INT d = n - which_block * block;
return d <= 0 ? 0 : (d > block ? block : d);
}
static INT num_blocks_kind(const ddim *dim, block_kind k)
{
return XM(num_blocks)(dim->n, dim->b[k]);
}
INT XM(num_blocks_total)(const dtensor *sz, block_kind k)
{
if (FINITE_RNK(sz->rnk)) {
int i;
INT ntot = 1;
for (i = 0; i < sz->rnk; ++i)
ntot *= num_blocks_kind(sz->dims + i, k);
return ntot;
}
else
return 0;
}
int XM(idle_process)(const dtensor *sz, block_kind k, int which_pe)
{
return (which_pe >= XM(num_blocks_total)(sz, k));
}
/* Given a non-idle process which_pe, computes the coordinate
vector coords[rnk] giving the coordinates of a block in the
matrix of blocks. k specifies whether we are talking about
the input or output data distribution. */
void XM(block_coords)(const dtensor *sz, block_kind k, int which_pe,
INT *coords)
{
int i;
A(!XM(idle_process)(sz, k, which_pe) && FINITE_RNK(sz->rnk));
for (i = sz->rnk - 1; i >= 0; --i) {
INT nb = num_blocks_kind(sz->dims + i, k);
coords[i] = which_pe % nb;
which_pe /= nb;
}
}
INT XM(total_block)(const dtensor *sz, block_kind k, int which_pe)
{
if (XM(idle_process)(sz, k, which_pe))
return 0;
else {
int i;
INT N = 1, *coords;
STACK_MALLOC(INT*, coords, sizeof(INT) * sz->rnk);
XM(block_coords)(sz, k, which_pe, coords);
for (i = 0; i < sz->rnk; ++i)
N *= XM(block)(sz->dims[i].n, sz->dims[i].b[k], coords[i]);
STACK_FREE(coords);
return N;
}
}
/* returns whether sz is local for dims >= dim */
int XM(is_local_after)(int dim, const dtensor *sz, block_kind k)
{
if (FINITE_RNK(sz->rnk))
for (; dim < sz->rnk; ++dim)
if (XM(num_blocks)(sz->dims[dim].n, sz->dims[dim].b[k]) > 1)
return 0;
return 1;
}
int XM(is_local)(const dtensor *sz, block_kind k)
{
return XM(is_local_after)(0, sz, k);
}
/* Return whether sz is distributed for k according to a simple
1d block distribution in the first or second dimensions */
int XM(is_block1d)(const dtensor *sz, block_kind k)
{
int i;
if (!FINITE_RNK(sz->rnk)) return 0;
for (i = 0; i < sz->rnk && num_blocks_kind(sz->dims + i, k) == 1; ++i) ;
return(i < sz->rnk && i < 2 && XM(is_local_after)(i + 1, sz, k));
}