Add GC stat: total_time_to_safepoint (JuliaLang#48867)

Author: vchuravy

base/timing.jl

@@ -20,6 +20,7 @@ struct GC_Num
     max_memory      ::Int64
     time_to_safepoint           ::Int64
     max_time_to_safepoint       ::Int64
+    total_time_to_safepoint     ::Int64
     sweep_time      ::Int64
     mark_time       ::Int64
     total_sweep_time  ::Int64

src/gc.c

@@ -3704,6 +3704,7 @@ JL_DLLEXPORT void jl_gc_collect(jl_gc_collection_t collection)
     if (duration > gc_num.max_time_to_safepoint)
         gc_num.max_time_to_safepoint = duration;
     gc_num.time_to_safepoint = duration;
+    gc_num.total_time_to_safepoint += duration;
 
     gc_invoke_callbacks(jl_gc_cb_pre_gc_t,
         gc_cblist_pre_gc, (collection));

src/gc.h

@@ -77,6 +77,7 @@ typedef struct {
     uint64_t    max_memory;
     uint64_t    time_to_safepoint;
     uint64_t    max_time_to_safepoint;
+    uint64_t    total_time_to_safepoint;
     uint64_t    sweep_time;
     uint64_t    mark_time;
     uint64_t    total_sweep_time;