first step outside @Elapsed

experiments/AMIP/coupler_driver.jl

@@ -710,8 +710,7 @@ function solve_coupler!(cs)
 
     ClimaComms.iamroot(comms_ctx) && @info("Starting coupling loop")
     ## step in time
-    ## Use ClimaComms.@elapsed to time the simulation on both CPU and GPU
-    walltime = ClimaComms.@elapsed comms_ctx.device for t in ((tspan[begin] + Δt_cpl):Δt_cpl:tspan[end])
+    for t in (tspan[begin]:Δt_cpl:tspan[end])
 
         cs.dates.date[1] = TimeManager.current_date(cs, t)
 
@@ -798,18 +797,29 @@ function solve_coupler!(cs)
         TimeManager.trigger_callback!(cs, cs.callbacks.checkpoint)
 
     end
-    ClimaComms.iamroot(comms_ctx) && @show(walltime)
 
-    return walltime
+    return nothing
 end
 
 ## exit if running performance anaysis #hide
 if haskey(ENV, "CI_PERF_SKIP_COUPLED_RUN") #hide
     throw(:exit_profile_init) #hide
 end #hide
 
-## run the coupled simulation
-walltime = solve_coupler!(cs);
+## run the coupled simulation for one timestep to precompile everything before timing
+cs.tspan[2] = Δt_cpl
+solve_coupler!(cs)
+
+## run the coupled simulation for the full timespan and time it
+cs.tspan[1] = Δt_cpl
+cs.tspan[2] = tspan[2]
+## Use ClimaComms.@elapsed to time the simulation on both CPU and GPU
+walltime = ClimaComms.@elapsed comms_ctx.device begin
+    s = CA.@timed_str begin
+        solve_coupler!(cs)
+    end
+end
+ClimaComms.iamroot(comms_ctx) && @show(walltime)
 
 ## Use ClimaAtmos calculation to show the simulated years per day of the simulation (SYPD)
 es = CA.EfficiencyStats(tspan, walltime)