Rename huge_threshold to experimental, and tweak documentation.

src/ctl.c

@@ -289,7 +289,7 @@ static const ctl_named_node_t opt_node[] = {
 	{NAME("dss"),		CTL(opt_dss)},
 	{NAME("narenas"),	CTL(opt_narenas)},
 	{NAME("percpu_arena"),	CTL(opt_percpu_arena)},
-	{NAME("huge_threshold"),	CTL(opt_huge_threshold)},
+	{NAME("experimental_huge_threshold"),	CTL(opt_huge_threshold)},
 	{NAME("background_thread"),	CTL(opt_background_thread)},
 	{NAME("max_background_threads"),	CTL(opt_max_background_threads)},
 	{NAME("dirty_decay_ms"), CTL(opt_dirty_decay_ms)},

src/jemalloc.c

@@ -1147,7 +1147,9 @@ malloc_conf_init(void) {
 			CONF_HANDLE_SSIZE_T(opt_lg_tcache_max, "lg_tcache_max",
 			    -1, (sizeof(size_t) << 3) - 1)
 
-			CONF_HANDLE_SIZE_T(opt_huge_threshold, "huge_threshold",
+			/* Experimental feature.  Will be documented later.*/
+			CONF_HANDLE_SIZE_T(opt_huge_threshold,
+			    "experimental_huge_threshold",
 			    LARGE_MINCLASS, LARGE_MAXCLASS, yes, yes, false)
 			CONF_HANDLE_SIZE_T(opt_lg_extent_max_active_fit,
 			    "lg_extent_max_active_fit", 0,

src/stats.c

@@ -910,7 +910,7 @@ stats_general_print(emitter_t *emitter) {
 	OPT_WRITE_CHAR_P("dss")
 	OPT_WRITE_UNSIGNED("narenas")
 	OPT_WRITE_CHAR_P("percpu_arena")
-	OPT_WRITE_UNSIGNED("huge_threshold")
+	OPT_WRITE_SIZE_T("experimental_huge_threshold")
 	OPT_WRITE_CHAR_P("metadata_thp")
 	OPT_WRITE_BOOL_MUTABLE("background_thread", "background_thread")
 	OPT_WRITE_SSIZE_T_MUTABLE("dirty_decay_ms", "arenas.dirty_decay_ms")