From 869910c1372547c34d365669fe6ce3e3b2d7bf27 Mon Sep 17 00:00:00 2001
From: Luca Bertagna <lbertag@sandia.gov>
Date: Thu, 9 May 2024 18:17:53 -0600
Subject: [PATCH] EAMxx: only init timestep in IO if this will be an output
 step

---
 .../eamxx/src/control/atmosphere_driver.cpp   |  2 +-
 .../src/share/io/scream_output_manager.cpp    | 19 +++++++++++++------
 .../src/share/io/scream_output_manager.hpp    |  2 +-
 .../eamxx/src/share/io/tests/io_diags.cpp     |  2 +-
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/components/eamxx/src/control/atmosphere_driver.cpp b/components/eamxx/src/control/atmosphere_driver.cpp
index 875f9878764..fc7ae4f8bce 100644
--- a/components/eamxx/src/control/atmosphere_driver.cpp
+++ b/components/eamxx/src/control/atmosphere_driver.cpp
@@ -1604,7 +1604,7 @@ void AtmosphereDriver::run (const int dt) {
   // the timestamp at the beginning of the timestep, so that we can compute
   // dt at the end.
   for (auto it : m_output_managers) {
-    it.init_timestep(m_current_ts);
+    it.init_timestep(m_current_ts,dt);
   }
 
   // The class AtmosphereProcessGroup will take care of dispatching arguments to
diff --git a/components/eamxx/src/share/io/scream_output_manager.cpp b/components/eamxx/src/share/io/scream_output_manager.cpp
index af5b67b12f6..7a96ddb8ae6 100644
--- a/components/eamxx/src/share/io/scream_output_manager.cpp
+++ b/components/eamxx/src/share/io/scream_output_manager.cpp
@@ -267,7 +267,7 @@ setup (const ekat::Comm& io_comm, const ekat::ParameterList& params,
     m_output_control.next_write_ts = m_run_t0;
     // This is in case some diags need to init the timestep. Most likely, their output
     // is meaningless at t0, but they may still require the start-of-step timestamp to be valid
-    init_timestep(m_run_t0);
+    init_timestep(m_run_t0,0);
     this->run(m_run_t0);
   }
 
@@ -285,13 +285,24 @@ add_global (const std::string& name, const ekat::any& global) {
 }
 
 /*===============================================================================================*/
-void OutputManager::init_timestep (const util::TimeStamp& start_of_step)
+void OutputManager::init_timestep (const util::TimeStamp& start_of_step, const Real dt)
 {
   // In case output is disabled, no point in doing anything else
   if (not m_output_control.output_enabled()) {
     return;
   }
 
+  // Update counters
+  ++m_output_control.nsamples_since_last_write;
+  ++m_checkpoint_control.nsamples_since_last_write;
+
+  // Check if the end of this timestep will correspond to an output step. If not, there's nothing to do
+  const auto& end_of_step = start_of_step+dt;
+  const bool will_be_output_step = m_output_control.is_write_step(end_of_step) || end_of_step==m_case_t0;
+  if (not will_be_output_step) {
+    return;
+  }
+
   if (m_atm_logger) {
     m_atm_logger->debug("[OutputManager::init_timestep] filename_prefix: " + m_filename_prefix + "\n");
   }
@@ -317,10 +328,6 @@ void OutputManager::run(const util::TimeStamp& timestamp)
   std::string timer_root = m_is_model_restart_output ? "EAMxx::IO::restart" : "EAMxx::IO::standard";
   start_timer(timer_root);
 
-  // Check if we need to open a new file
-  ++m_output_control.nsamples_since_last_write;
-  ++m_checkpoint_control.nsamples_since_last_write;
-
   // Check if this is a write step (and what kind)
   // Note: a full checkpoint not only writes globals in the restart file, but also all the history variables.
   //       Since we *always* write a history restart file, we can have a non-full checkpoint, if the average
diff --git a/components/eamxx/src/share/io/scream_output_manager.hpp b/components/eamxx/src/share/io/scream_output_manager.hpp
index df54f614970..e1f58d93fed 100644
--- a/components/eamxx/src/share/io/scream_output_manager.hpp
+++ b/components/eamxx/src/share/io/scream_output_manager.hpp
@@ -113,7 +113,7 @@ class OutputManager
   }
   void add_global (const std::string& name, const ekat::any& global);
 
-  void init_timestep (const util::TimeStamp& start_of_step);
+  void init_timestep (const util::TimeStamp& start_of_step, const Real dt);
   void run (const util::TimeStamp& current_ts);
   void finalize();
 
diff --git a/components/eamxx/src/share/io/tests/io_diags.cpp b/components/eamxx/src/share/io/tests/io_diags.cpp
index b9477413a21..3b67e9419d5 100644
--- a/components/eamxx/src/share/io/tests/io_diags.cpp
+++ b/components/eamxx/src/share/io/tests/io_diags.cpp
@@ -207,7 +207,7 @@ void write (const int seed, const ekat::Comm& comm)
     f.get_header().get_tracking().update_time_stamp(t0+dt);
     f.update(one,1.0,1.0);
   }
-  om.init_timestep(t0);
+  om.init_timestep(t0,dt);
   om.run (t0+dt);
 
   // Close file and cleanup