Add a new function to split by the median

MalachiTimothyPhillips · Feb 9, 2019 · a883699 · a883699
1 parent d887019
commit a883699
Showing 1 changed file with 39 additions and 46 deletions.
diff --git a/src/genmap-algo.c b/src/genmap-algo.c
@@ -220,6 +220,38 @@ int GenmapFiedler(GenmapHandle h, GenmapComm c, int maxIter, int global) {
  return iter;
 }
 
+void GenmapSplitByMedian(GenmapHandle h, int *bin) {
+ GenmapLong start = GenmapGetLocalStartIndex(h);
+ GenmapLong nel = GenmapGetNGlobalElements(h);
+ GenmapLong id = GenmapCommRank(GenmapGetLocalComm(h));
+ GenmapLong np = GenmapCommSize(GenmapGetLocalComm(h));
+ GenmapInt lelt = GenmapGetNLocalElements(h);
+ GenmapElements elements = GenmapGetElements(h);
+
+ if(id < (np + 1) / 2)
+ *bin = 0;
+ else
+ *bin = 1;
+
+ GenmapInt pNel = (GenmapInt)(nel / np);
+ GenmapInt nrem = (GenmapInt)(nel - pNel * np);
+ GenmapInt idCount = 0;
+ while(idCount * pNel + ((idCount < nrem) ? idCount : nrem) < start)
+ idCount++;
+
+ GenmapLong upLimit = idCount * pNel + ((idCount < nrem) ? idCount : nrem);
+ GenmapLong downLimit = start;
+ do {
+ GenmapInt end = upLimit - start < lelt ? (GenmapInt)(upLimit - start) : lelt;
+ GenmapInt i;
+ for(i = (GenmapInt)(downLimit - start); i < end; i++)
+ elements[i].proc = idCount - 1;
+ downLimit = upLimit;
+ idCount++;
+ upLimit = idCount * pNel + ((idCount < nrem) ? idCount : nrem);
+ } while(downLimit - start < lelt);
+}
+
 void GenmapAssignBins(GenmapHandle h, int field, buffer *buf0) {
  GenmapElements elements = GenmapGetElements(h);
  GenmapInt lelt = GenmapGetNLocalElements(h);
@@ -272,13 +304,8 @@ void GenmapBinSort(GenmapHandle h, int field, buffer *buf0) {
 
 
 void GenmapRSB(GenmapHandle h) {
- GenmapLong id, np, nel, start;
- GenmapInt lelt;
- GenmapElements elements;
-
  int maxIter = 50;
- int iter = maxIter;
- int npass = 50, ipass = 0;
+ int npass = 50;
 
  if(GenmapCommRank(GenmapGetGlobalComm(h)) == 0 && h->dbgLevel > 0)
  printf("running RSB "), fflush(stdout);
@@ -297,7 +324,8 @@ void GenmapRSB(GenmapHandle h) {
  GenmapGetGlobalComm(h)));
 #endif
 
- ipass = 0;
+ int ipass = 0;
+ int iter;
  do {
  iter = GenmapFiedler(h, GenmapGetLocalComm(h), maxIter, global);
  ipass++;
@@ -306,48 +334,13 @@ void GenmapRSB(GenmapHandle h) {
 
  GenmapBinSort(h, 0, &buf0);
 
- lelt = GenmapGetNLocalElements(h);
- start = GenmapGetLocalStartIndex(h);
- nel = GenmapGetNGlobalElements(h);
- id = GenmapCommRank(GenmapGetLocalComm(h));
- np = GenmapCommSize(GenmapGetLocalComm(h));
- elements = GenmapGetElements(h);
-
- GenmapInt bin;
- if(id < (np + 1) / 2)
- bin = 0;
- else
- bin = 1;
-
- GenmapInt pNel = (GenmapInt)(nel / np);
- GenmapInt nrem = (GenmapInt)(nel - pNel * np);
- GenmapInt idCount = 0;
- while(idCount * pNel + ((idCount < nrem) ? idCount : nrem) < start)
- idCount++;
-
- GenmapLong upLimit = idCount * pNel + ((idCount < nrem) ? idCount : nrem);
- GenmapLong downLimit = start;
- do {
- GenmapInt end = upLimit - start < lelt ? (GenmapInt)(upLimit - start) : lelt;
- GenmapInt i;
- for(i = (GenmapInt)(downLimit - start); i < end; i++)
- elements[i].proc = idCount - 1;
- downLimit = upLimit;
- idCount++;
- upLimit = idCount * pNel + ((idCount < nrem) ? idCount : nrem);
- } while(downLimit - start < lelt);
-
- sarray_transfer(struct GenmapElement_private, &(h->elementArray), proc, 0,
- &(h->cr));
- elements = GenmapGetElements(h);
- lelt = GenmapGetNLocalElements(h);
-
- // sort locally again -- now we have everything sorted
- sarray_sort_2(struct GenmapElement_private, elements, (GenmapUInt)lelt, fiedler,
- TYPE_DOUBLE, globalId, TYPE_LONG, &buf0);
+ int bin;
+ GenmapSplitByMedian(h, &bin);
+ GenmapTransferToBins(h, 0, &buf0);
 
  // Now it is time to split the communicator
  GenmapCommExternal local;
+ GenmapLong id = GenmapCommRank(GenmapGetLocalComm(h));
 #if defined(GENMAP_MPI)
  MPI_Comm_split(h->local->gsComm.c, bin, id, &local);
 #else