Name
HPL_pdlaswp01N Broadcast a column panel L and swap the row panel U.
Synopsis
#include "hpl.h"
void
HPL_pdlaswp01N(
HPL_T_panel *
PBCST,
int *
IFLAG,
HPL_T_panel *
PANEL,
const int
NN
);
Description
HPL_pdlaswp01N
applies the  NB  row interchanges to  NN columns of the
trailing submatrix and broadcast a column panel.
 
A "Spread then roll" algorithm performs  the swap :: broadcast  of the
row panel U at once,  resulting in a minimal communication volume  and
a "very good"  use of the connectivity if available.  With  P  process
rows  and  assuming  bi-directional links,  the  running time  of this
function can be approximated by:
 
   (log_2(P)+(P-1)) * lat +   K * NB * LocQ(N) / bdwth
 
where  NB  is the number of rows of the row panel U,  N is the global
number of columns being updated,  lat and bdwth  are the latency  and
bandwidth  of  the  network  for  double  precision real words.  K is
a constant in (2,3] that depends on the achieved bandwidth  during  a
simultaneous  message exchange  between two processes.  An  empirical
optimistic value of K is typically 2.4.
Arguments
PBCST   (local input/output)          HPL_T_panel *
        On entry,  PBCST  points to the data structure containing the
        panel (to be broadcast) information.
IFLAG   (local input/output)          int *
        On entry, IFLAG  indicates  whether or not  the broadcast has
        already been completed.  If not,  probing will occur, and the
        outcome will be contained in IFLAG on exit.
PANEL   (local input/output)          HPL_T_panel *
        On entry,  PANEL  points to the data structure containing the
        panel information.
NN      (local input)                 const int
        On entry, NN specifies  the  local  number  of columns of the
        trailing  submatrix  to  be swapped and broadcast starting at
        the current position. NN must be at least zero.
See Also
HPL_pdgesv,
HPL_pdgesvK2,
HPL_pdupdateNN,
HPL_pdupdateTN,
HPL_pipid,
HPL_plindx1,
HPL_plindx10,
HPL_spreadN,
HPL_equil,
HPL_rollN,
HPL_dlaswp00N,
HPL_dlaswp01N,
HPL_dlaswp06N.