Add RSS memory usage to reporting

src/callbacks/callbacks.jl

@@ -10,6 +10,7 @@ import SciMLBase
 import .Parameters as CAP
 import DiffEqCallbacks as DECB
 import ClimaCore: InputOutput
+import Base.Sys: maxrss
 using Dates
 using Insolation: instantaneous_zenith_angle
 import ClimaCore.Fields: ColumnField
@@ -502,6 +503,14 @@ function print_walltime_estimate(integrator)
             wall_time_spent percent_complete = "$percent_complete%" sypd = sypd date_now =
             Dates.now() estimated_finish_date = estimated_finish_date
 
+        maxrss_bytes = maxrss()
+        maxrss_str =
+            maxrss_bytes > 2^30 ?
+            "$(round(maxrss_bytes / 2^30, digits = 2)) GiB" :
+            "$(round(maxrss_bytes / 2^20, digits = 2)) MiB"
+
+        @info "Memory used by process (RSS): $maxrss_str"
+
         # the first fixed increment is equivalent to
         # doubling (which puts us at 10%), so we check
         # if we're below 5%.