do not show warning for balance issues on cpus

Author: glesur

src/timeIntegrator.cpp

@@ -197,47 +197,53 @@ double TimeIntegrator::ComputeBalance() {
   // Check MPI imbalance
     double imbalance = 0;
     #ifdef WITH_MPI
-      const double allowedImbalance = 20.0;
-      std::vector<double> computeLogPerCore(idfx::psize);
-      MPI_Gather(&computeLastLog, 1, MPI_DOUBLE, computeLogPerCore.data(), 1, MPI_DOUBLE, 0,
-                  MPI_COMM_WORLD);
-      computeLastLog = 0; // reset timer for all cores
-      if(idfx::prank==0) {
-        // Compute the average, the min and the max
-        double computeMin = computeLogPerCore[0];
-        double computeMax = computeLogPerCore[0];
-        double computeMean = 0;
-
-        for(int i = 0 ; i < idfx::psize ; i++) {
-          computeMean += computeLogPerCore[i];
-          if(computeLogPerCore[i]>computeMax) {
-            computeMax = computeLogPerCore[i];
-          }
-          if(computeLogPerCore[i]<computeMin) {
-            computeMin = computeLogPerCore[i];
-          }
-        }
-        computeMean /= idfx::psize;
-        imbalance = (computeMax-computeMin)/computeMean*100;
+      // only do this on GPUs
+      #if defined(KOKKOS_ENABLE_CUDA) || defined(KOKKOS_ENABLE_HIP) || defined(KOKKOS_ENABLE_SYCL)
+        const double allowedImbalance = 20.0;
+        std::vector<double> computeLogPerCore(idfx::psize);
+        MPI_Gather(&computeLastLog, 1, MPI_DOUBLE, computeLogPerCore.data(), 1, MPI_DOUBLE, 0,
+                    MPI_COMM_WORLD);
+        computeLastLog = 0; // reset timer for all cores
+        if(idfx::prank==0) {
+          // Compute the average, the min and the max
+          double computeMin = computeLogPerCore[0];
+          double computeMax = computeLogPerCore[0];
+          double computeMean = 0;
 
-        if(imbalance>allowedImbalance ) {
-          idfx::cout << "-------------------------------------------------------------"<< std::endl;
-          idfx::cout << "Warning: MPI imbalance found in this run " << std::endl;
-          idfx::cout << std::fixed;
           for(int i = 0 ; i < idfx::psize ; i++) {
-            if(computeLogPerCore[i]/computeMean - 1> allowedImbalance/2/100) {
-              idfx::cout << "+" << 100*(computeLogPerCore[i]/computeMean-1)
-                        << "% (proc " << i << ")" << std::endl;
+            computeMean += computeLogPerCore[i];
+            if(computeLogPerCore[i]>computeMax) {
+              computeMax = computeLogPerCore[i];
             }
-            if(1-computeLogPerCore[i]/computeMean > allowedImbalance/2/100) {
-              idfx::cout << "-" << 100*(1-computeLogPerCore[i]/computeMean)
-                                << "% (proc " << i << ")" << std::endl;
+            if(computeLogPerCore[i]<computeMin) {
+              computeMin = computeLogPerCore[i];
             }
           }
-          idfx::cout << "You should probably check these nodes are running properly." << std::endl;
-          idfx::cout << "-------------------------------------------------------------"<< std::endl;
+          computeMean /= idfx::psize;
+          imbalance = (computeMax-computeMin)/computeMean*100;
+
+          if(imbalance>allowedImbalance ) {
+            idfx::cout << "-------------------------------------------------------------"
+                       << std::endl;
+            idfx::cout << "Warning: MPI imbalance found in this run " << std::endl;
+            idfx::cout << std::fixed;
+            for(int i = 0 ; i < idfx::psize ; i++) {
+              if(computeLogPerCore[i]/computeMean - 1> allowedImbalance/2/100) {
+                idfx::cout << "+" << 100*(computeLogPerCore[i]/computeMean-1)
+                          << "% (proc " << i << ")" << std::endl;
+              }
+              if(1-computeLogPerCore[i]/computeMean > allowedImbalance/2/100) {
+                idfx::cout << "-" << 100*(1-computeLogPerCore[i]/computeMean)
+                                  << "% (proc " << i << ")" << std::endl;
+              }
+            }
+            idfx::cout << "You should probably check these nodes are running properly."
+                       << std::endl;
+            idfx::cout << "-------------------------------------------------------------"
+                       << std::endl;
+          }
         }
-      }
+      #endif
     #endif
     return(imbalance);
 }