# HG changeset patch
# User vladidan
# Date 1367357761 14400
# Node ID b4081e9714ec297ffdd8de555dd0a179b36b60f1
# Parent  ed5a590835a4c18512e89922e69523f845040693
8013398: Adjust number of stack guard pages on systems with large memory page size
Summary: Auto adjust number of stack guard pages on systems with large memory page size
Reviewed-by: bobv, coleenp

diff -r ed5a590835a4 -r b4081e9714ec src/os/linux/vm/os_linux.cpp
--- a/src/os/linux/vm/os_linux.cpp	Tue Apr 30 09:17:06 2013 -0400
+++ b/src/os/linux/vm/os_linux.cpp	Tue Apr 30 17:36:01 2013 -0400
@@ -119,6 +119,7 @@
 Mutex* os::Linux::_createThread_lock = NULL;
 pthread_t os::Linux::_main_thread;
 int os::Linux::_page_size = -1;
+const int os::Linux::_vm_default_page_size = (8 * K);
 bool os::Linux::_is_floating_stack = false;
 bool os::Linux::_is_NPTL = false;
 bool os::Linux::_supports_fast_thread_cpu_time = false;
@@ -4250,6 +4251,15 @@
   Linux::clock_init();
   initial_time_count = os::elapsed_counter();
   pthread_mutex_init(&dl_mutex, NULL);
+
+  // If the pagesize of the VM is greater than 8K determine the appropriate
+  // number of initial guard pages.  The user can change this with the
+  // command line arguments, if needed.
+  if (vm_page_size() > (int)Linux::vm_default_page_size()) {
+    StackYellowPages = 1;
+    StackRedPages = 1;
+    StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
+  }
 }
 
 // To install functions for atexit system call
@@ -4303,8 +4313,8 @@
   // Add in 2*BytesPerWord times page size to account for VM stack during
   // class initialization depending on 32 or 64 bit VM.
   os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
-            (size_t)(StackYellowPages+StackRedPages+StackShadowPages+
-                    2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size());
+            (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
+                    (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
 
   size_t threadStackSizeInBytes = ThreadStackSize * K;
   if (threadStackSizeInBytes != 0 &&
diff -r ed5a590835a4 -r b4081e9714ec src/os/linux/vm/os_linux.hpp
--- a/src/os/linux/vm/os_linux.hpp	Tue Apr 30 09:17:06 2013 -0400
+++ b/src/os/linux/vm/os_linux.hpp	Tue Apr 30 17:36:01 2013 -0400
@@ -70,6 +70,7 @@
   static pthread_t _main_thread;
   static Mutex* _createThread_lock;
   static int _page_size;
+  static const int _vm_default_page_size;
 
   static julong available_memory();
   static julong physical_memory() { return _physical_memory; }
@@ -116,6 +117,8 @@
   static int page_size(void)                                        { return _page_size; }
   static void set_page_size(int val)                                { _page_size = val; }
 
+  static int vm_default_page_size(void)                             { return _vm_default_page_size; }
+
   static address   ucontext_get_pc(ucontext_t* uc);
   static intptr_t* ucontext_get_sp(ucontext_t* uc);
   static intptr_t* ucontext_get_fp(ucontext_t* uc);