8254699: Suboptimal PreTouchParallelChunkSize defaults and limits

Reviewed-by: tschatzl, sjohanss

src/hotspot/os/aix/globals_aix.hpp

@@ -86,6 +86,7 @@
 
 // UseLargePages means nothing, for now, on AIX.
 // Use Use64KPages or Use16MPages instead.
+define_pd_global(size_t, PreTouchParallelChunkSize, 1 * G);
 define_pd_global(bool, UseLargePages, false);
 define_pd_global(bool, UseLargePagesIndividualAllocation, false);
 define_pd_global(bool, UseThreadPriorities, true) ;

src/hotspot/os/bsd/globals_bsd.hpp

@@ -42,6 +42,7 @@
 // Defines Bsd-specific default values. The flags are available on all
 // platforms, but they may have different default values on other platforms.
 //
+define_pd_global(size_t, PreTouchParallelChunkSize, 1 * G);
 define_pd_global(bool, UseLargePages, false);
 define_pd_global(bool, UseLargePagesIndividualAllocation, false);
 define_pd_global(bool, UseThreadPriorities, true) ;

src/hotspot/os/linux/globals_linux.hpp

@@ -90,6 +90,7 @@
 // Defines Linux-specific default values. The flags are available on all
 // platforms, but they may have different default values on other platforms.
 //
+define_pd_global(size_t, PreTouchParallelChunkSize, 4 * M);
 define_pd_global(bool, UseLargePages, false);
 define_pd_global(bool, UseLargePagesIndividualAllocation, false);
 define_pd_global(bool, UseThreadPriorities, true) ;

src/hotspot/os/windows/globals_windows.hpp

@@ -45,6 +45,7 @@ product(bool, UseOSErrorReporting, false,                                 \
 // Defines Windows-specific default values. The flags are available on all
 // platforms, but they may have different default values on other platforms.
 //
+define_pd_global(size_t, PreTouchParallelChunkSize, 1 * G);
 define_pd_global(bool, UseLargePages, false);
 define_pd_global(bool, UseLargePagesIndividualAllocation, true);
 define_pd_global(bool, UseThreadPriorities, true) ;

src/hotspot/share/gc/shared/gc_globals.hpp

@@ -200,9 +200,9 @@
   product(bool, AlwaysPreTouch, false,                                      \
           "Force all freshly committed pages to be pre-touched")            \
                                                                             \
-  product(size_t, PreTouchParallelChunkSize, 1 * G,                         \
+  product_pd(size_t, PreTouchParallelChunkSize,                             \
           "Per-thread chunk size for parallel memory pre-touch.")           \
-          range(1, SIZE_MAX / 2)                                            \
+          range(4*K, SIZE_MAX / 2)                                          \
                                                                             \
   /* where does the range max value of (max_jint - 1) come from? */         \
   product(size_t, MarkStackSizeMax, NOT_LP64(4*M) LP64_ONLY(512*M),         \