From 09b937c022fb9f44a4ef581e9730a79b440f035d Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 25 Feb 2026 12:42:47 +0000
Subject: [PATCH] Fix timing: replace clock() with MPI_Wtime() for wall-clock
 measurement

clock() measures total CPU time across all threads, not wall-clock
time. With the new OpenMP parallel regions in bssn_rhs_c.C, clock()
sums CPU time from all OpenMP threads, producing inflated timing that
scales with thread count rather than reflecting actual elapsed time.

MPI_Wtime() returns wall-clock seconds, giving accurate timing
regardless of the number of OpenMP threads running inside the
measured interval.

Co-authored-by: ianchb <i@4t.pw>
---
 AMSS_NCKU_source/bssn_class.C   | 112 ++++++++++++++++----------------
 AMSS_NCKU_source/scalar_class.C |  48 +++++++-------
 2 files changed, 80 insertions(+), 80 deletions(-)

diff --git a/AMSS_NCKU_source/bssn_class.C b/AMSS_NCKU_source/bssn_class.C
index eb84f8e..e8041b5 100644
--- a/AMSS_NCKU_source/bssn_class.C
+++ b/AMSS_NCKU_source/bssn_class.C
@@ -2028,7 +2028,7 @@ void bssn_class::Read_Ansorg()
 
 void bssn_class::Evolve(int Steps)
 {
-  clock_t prev_clock, curr_clock;
+  double prev_clock, curr_clock;
   double LastDump = 0.0, LastCheck = 0.0, Last2dDump = 0.0;
   LastAnas = 0;
 #if 0
@@ -2142,7 +2142,7 @@ void bssn_class::Evolve(int Steps)
     //     { GH->levels=GH->movls; }
 
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
 #if (PSTR == 0)
     RecursiveStep(0);
 #elif (PSTR == 1 || PSTR == 2 || PSTR == 3)
@@ -2198,10 +2198,10 @@ void bssn_class::Evolve(int Steps)
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
       cout << endl;
       cout << " Timestep # " << ncount << ": integrating to time: " << PhysTime << "   "
-           << " Computer used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+           << " Computer used " << (curr_clock - prev_clock) 
            << " seconds! " << endl;
       // cout << endl;
     }
@@ -2403,15 +2403,15 @@ void bssn_class::RecursiveStep(int lev)
 #ifdef WithShell
     if (lev == 0)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->CS_Inter(StateList, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
-        cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+        curr_clock = MPI_Wtime();
+        cout << " CS_Inter used " << (curr_clock - prev_clock) << " seconds! " << endl;
       }
     }
 #endif
@@ -2543,15 +2543,15 @@ void bssn_class::ParallelStep()
     SHStep();
 #if (RPS == 1)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->CS_Inter(StateList, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
-        cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+        curr_clock = MPI_Wtime();
+        cout << " CS_Inter used " << (curr_clock - prev_clock) << " seconds! " << endl;
       }
     }
 #endif
@@ -2846,15 +2846,15 @@ void bssn_class::ParallelStep()
 
 #if (RPS == 1)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(StateList, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) 
            << " seconds! " << endl;
     }
     //               a_stream.clear();
@@ -3355,16 +3355,16 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->Synch(SynchList_pre, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
       cout << " Shell stuff synchronization used "
-           << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+           << (curr_clock - prev_clock)
            << " seconds! " << endl;
     }
   }
@@ -3715,16 +3715,16 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
     if (lev == 0)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->Synch(SynchList_cor, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
         cout << " Shell stuff synchronization used "
-             << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+             << (curr_clock - prev_clock)
              << " seconds! " << endl;
       }
     }
@@ -3842,15 +3842,15 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) 
            << " seconds! " << endl;
     }
   }
@@ -4214,16 +4214,16 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->Synch(SynchList_pre, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
       cout << " Shell stuff synchronization used "
-           << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+           << (curr_clock - prev_clock)
            << " seconds! " << endl;
     }
   }
@@ -4559,16 +4559,16 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
     if (lev == 0)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->Synch(SynchList_cor, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
         cout << " Shell stuff synchronization used "
-             << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+             << (curr_clock - prev_clock)
              << " seconds! " << endl;
       }
     }
@@ -4679,15 +4679,15 @@ void bssn_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) 
            << " seconds! " << endl;
     }
   }
@@ -5476,16 +5476,16 @@ void bssn_class::SHStep()
   }
 
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->Synch(SynchList_pre, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
       cout << " Shell stuff synchronization used "
-           << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+           << (curr_clock - prev_clock)
            << " seconds! " << endl;
     }
   }
@@ -5653,16 +5653,16 @@ void bssn_class::SHStep()
     }
 
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->Synch(SynchList_cor, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
         cout << " Shell stuff synchronization used "
-             << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC)
+             << (curr_clock - prev_clock)
              << " seconds! " << endl;
       }
     }
@@ -5698,15 +5698,15 @@ void bssn_class::SHStep()
   }
 #if (RPS == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) 
            << " seconds! " << endl;
     }
   }
@@ -7639,9 +7639,9 @@ void bssn_class::AH_Step_Find(int lev, double dT_lev)
     }
     if (tf)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        prev_clock = clock();
+        prev_clock = MPI_Wtime();
       const int cdumpid = int(PhysTime / AHdumptime) + 1;
       for (int ihn = 0; ihn < HN_num; ihn++)
         dumpid[ihn] = cdumpid;
@@ -7720,9 +7720,9 @@ void bssn_class::AH_Step_Find(int lev, double dT_lev)
 
       if (myrank == 0)
       {
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
         cout << " Finding horizon used " 
-             << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) 
+             << (curr_clock - prev_clock) 
              << " seconds! " << endl;
       }
     }
diff --git a/AMSS_NCKU_source/scalar_class.C b/AMSS_NCKU_source/scalar_class.C
index d0cdec0..6715b62 100644
--- a/AMSS_NCKU_source/scalar_class.C
+++ b/AMSS_NCKU_source/scalar_class.C
@@ -319,7 +319,7 @@ void scalar_class::Setup_Initial_Data()
 }
 void scalar_class::Evolve(int Steps)
 {
-  clock_t prev_clock, curr_clock;
+  double prev_clock, curr_clock;
   double LastDump = 0.0, LastCheck = 0.0;
   LastAnas = 0;
 
@@ -328,7 +328,7 @@ void scalar_class::Evolve(int Steps)
   for (int ncount = 1; ncount < Steps + 1; ncount++)
   {
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     RecursiveStep(0);
 
     LastDump += dT_mon;
@@ -346,9 +346,9 @@ void scalar_class::Evolve(int Steps)
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
       cout << " Timestep # " << ncount << ": integrating to time: " << PhysTime
-           << " Computer used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+           << " Computer used " << (curr_clock - prev_clock) << " seconds! " << endl;
     }
     if (PhysTime >= TotalTime)
       break;
@@ -549,15 +549,15 @@ void scalar_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->Synch(SynchList_pre, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " Shell stuff synchronization used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+      curr_clock = MPI_Wtime();
+      cout << " Shell stuff synchronization used " << (curr_clock - prev_clock) << " seconds! " << endl;
     }
   }
 #endif
@@ -731,15 +731,15 @@ void scalar_class::Step(int lev, int YN)
 #ifdef WithShell
     if (lev == 0)
     {
-      clock_t prev_clock, curr_clock;
+      double prev_clock, curr_clock;
       if (myrank == 0)
-        curr_clock = clock();
+        curr_clock = MPI_Wtime();
       SH->Synch(SynchList_cor, Symmetry);
       if (myrank == 0)
       {
         prev_clock = curr_clock;
-        curr_clock = clock();
-        cout << " Shell stuff synchronization used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+        curr_clock = MPI_Wtime();
+        cout << " Shell stuff synchronization used " << (curr_clock - prev_clock) << " seconds! " << endl;
       }
     }
 #endif
@@ -786,15 +786,15 @@ void scalar_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) << " seconds! " << endl;
     }
   }
 #endif
@@ -1010,15 +1010,15 @@ void scalar_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->Synch(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " Shell stuff synchronization used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+      curr_clock = MPI_Wtime();
+      cout << " Shell stuff synchronization used " << (curr_clock - prev_clock) << " seconds! " << endl;
     }
   }
 #endif
@@ -1027,15 +1027,15 @@ void scalar_class::Step(int lev, int YN)
 #ifdef WithShell
   if (lev == 0)
   {
-    clock_t prev_clock, curr_clock;
+    double prev_clock, curr_clock;
     if (myrank == 0)
-      curr_clock = clock();
+      curr_clock = MPI_Wtime();
     SH->CS_Inter(SynchList_cor, Symmetry);
     if (myrank == 0)
     {
       prev_clock = curr_clock;
-      curr_clock = clock();
-      cout << " CS_Inter used " << (double)(curr_clock - prev_clock) / ((double)CLOCKS_PER_SEC) << " seconds! " << endl;
+      curr_clock = MPI_Wtime();
+      cout << " CS_Inter used " << (curr_clock - prev_clock) << " seconds! " << endl;
     }
   }
 #endif