From 4e8af7be06b83b58d7610ca28070f5f6971eb49c Mon Sep 17 00:00:00 2001
From: Stefan <stgeke@gmail.com>
Date: Sun, 1 Nov 2020 07:44:39 +0100
Subject: [PATCH] print warning if Lanczos did not converge

---
 src/genmap-impl.h       |  2 ++
 src/genmap-rsb.c        | 13 +++++++++++++
 src/genmap-statistics.c |  8 ++++++++
 3 files changed, 23 insertions(+)

diff --git a/src/genmap-impl.h b/src/genmap-impl.h
index 58fd9901e..73a7b8669 100644
--- a/src/genmap-impl.h
+++ b/src/genmap-impl.h
@@ -80,7 +80,9 @@ void metric_finalize();
 void metric_acc(metric m,double count);
 void metric_tic(struct comm *c,metric m);
 void metric_toc(struct comm *c,metric m);
+double metric_get_value(int level,metric m);
 void metric_push_level();
+uint metric_get_levels();
 void metric_print(struct comm *c);
 
 struct GenmapHandle_private {
diff --git a/src/genmap-rsb.c b/src/genmap-rsb.c
index e2a60e0ae..36fe214cb 100644
--- a/src/genmap-rsb.c
+++ b/src/genmap-rsb.c
@@ -77,6 +77,19 @@ void GenmapRSB(GenmapHandle h,int verbose){
     metric_push_level();
   }
 
+  sint converged=1,buf;
+  for(i=0; i<metric_get_levels(); i++){
+    int val=(int)metric_get_value(i,NFIEDLER);
+    if(val>=npass*maxIter){
+      converged=0;
+      break;
+    }
+  }
+  comm_allreduce(&global_c->gsc,gs_int,gs_min,&converged,1,&buf);// min
+  if(converged==0 && GenmapCommRank(global_c)==0){
+    printf("WARNING: Lanczos failed to converge during partitioning!");
+  }
+
   //metric_print(&global_c->gsc);
   metric_finalize();
 
diff --git a/src/genmap-statistics.c b/src/genmap-statistics.c
index d87ead48c..b071eff36 100644
--- a/src/genmap-statistics.c
+++ b/src/genmap-statistics.c
@@ -37,6 +37,10 @@ void metric_toc(struct comm *c,metric m){
   comm_barrier(c);
 }
 
+double metric_get_value(int level,metric m){
+  return stack[level*MAXMETS+m];
+}
+
 void metric_push_level(){
   assert(stack_size<=stack_max && "stack_size > stack_max");
 
@@ -52,6 +56,10 @@ void metric_push_level(){
   stack_size++;
 }
 
+uint metric_get_levels(){
+  return stack_size;
+}
+
 void metric_print(struct comm *c){
   double min[MAXSIZE],max[MAXSIZE],sum[MAXSIZE],buf[MAXSIZE];
   uint max_size=stack_size*MAXMETS;