Chooses machine-dependent parameters for the local environment. More...
#include "superlu_ddefs.h"#include "machines.h"#include <stdlib.h>#include <stdio.h>
Functions | |
| int | sp_ienv_dist (int ispec, superlu_dist_options_t *options) |
Detailed Description
Chooses machine-dependent parameters for the local environment.
Copyright (c) 2003, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from U.S. Dept. of Energy)
All rights reserved.
The source code is distributed under BSD license, see the file License.txt at the top-level directory.
Function Documentation
◆ sp_ienv_dist()
| int sp_ienv_dist | ( | int | ispec, |
| superlu_dist_options_t * | options | ||
| ) |
Purpose
sp_ienv_dist() is inquired to choose machine-dependent integer parameters for the local environment. See ISPEC for a description of the parameters.
This version provides a set of parameters which should give good,
but not optimal, performance on many of the currently available
computers. Users are encouraged to set the environment variable to change the tuning parameters for their particular machines.
Arguments
ISPEC (input) int Specifies the parameter to be returned as the value of SP_IENV_DIST.
= 1: the panel size w; a panel consists of w consecutive columns of matrix A in the process of Gaussian elimination. The best value depends on machine's cache characters. = 2: the relaxation parameter relax; if the number of nodes (columns) in a subtree of the elimination tree is less than relax, this subtree is considered as one supernode, regardless of the their row structures. = 3: the maximum size for a supernode, which must be greater than or equal to relaxation parameter (see case 2); = 4: the minimum row dimension for 2-D blocking to be used; = 5: the minimum column dimension for 2-D blocking to be used; = 6: the estimated fills factor for the adjacency structures of L and U, compared with A; = 7: the minimum value of the product M*N*K for a GEMM call worth being offloaded to accelerator (e.g., GPU, Xeon Phi). = 8: the maximum buffer size on GPU that can hold the "dC" matrix in the GEMM call for the Schur complement update. If this is too small, the Schur complement update will be done in multiple partitions, may be slower. = 9: number of GPU streams = 10: whether to offload work to GPU or not
options (input) superlu_dist_options_t* The structure defines the input parameters to control how the LU decomposition the solves are performed.
(SP_IENV_DIST) (output) int >= 0: the value of the parameter specified by ISPEC
< 0: if SP_IENV_DIST = -k, the k-th argument had an illegal value.
