Add a proper way to pass the number of processors to V8

BUG=321060
LOG=n
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/73463004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17874 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -3809,8 +3809,13 @@ class V8_EXPORT ResourceConstraints {
    *
    * \param physical_memory The total amount of physical memory on the current
    *   device, in bytes.
+   * \param number_of_processors The number of CPUs available on the current
+   *   device.
    */
-  void ConfigureDefaults(uint64_t physical_memory);
+  void ConfigureDefaults(uint64_t physical_memory,
+                         uint32_t number_of_processors);
+  V8_DEPRECATED("Will be removed",
+                void ConfigureDefaults(uint64_t physical_memory));
 
   int max_young_space_size() const { return max_young_space_size_; }
   void set_max_young_space_size(int value) { max_young_space_size_ = value; }

src/api.cc

@@ -566,8 +566,8 @@ ResourceConstraints::ResourceConstraints()
     stack_limit_(NULL),
     max_available_threads_(0) { }
 
-
-void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory) {
+void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory,
+                                            uint32_t number_of_processors) {
   const int lump_of_memory = (i::kPointerSize / 4) * i::MB;
 #if V8_OS_ANDROID
   // Android has higher physical memory requirements before raising the maximum
@@ -601,7 +601,12 @@ void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory) {
     set_max_executable_size(256 * lump_of_memory);
   }
 
-  set_max_available_threads(0);
+  set_max_available_threads(i::Max(i::Min(number_of_processors, 4u), 1u));
+}
+
+
+void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory) {
+  ConfigureDefaults(physical_memory, i::CPU::NumberOfProcessorsOnline());
 }
 
 

src/d8.cc

@@ -62,6 +62,7 @@
 #ifndef V8_SHARED
 #include "api.h"
 #include "checks.h"
+#include "cpu.h"
 #include "d8-debug.h"
 #include "debug.h"
 #include "natives.h"
@@ -1709,7 +1710,8 @@ int Shell::Main(int argc, char* argv[]) {
   Isolate* isolate = Isolate::GetCurrent();
 #ifndef V8_SHARED
   v8::ResourceConstraints constraints;
-  constraints.ConfigureDefaults(i::OS::TotalPhysicalMemory());
+  constraints.ConfigureDefaults(i::OS::TotalPhysicalMemory(),
+                                i::CPU::NumberOfProcessorsOnline());
   v8::SetResourceConstraints(isolate, &constraints);
 #endif
   DumbLineEditor dumb_line_editor(isolate);