src/cpu/x86/vm/vm_version_x86.cpp

rev 2190 : make no sw prefetch default for family 15h
rev 2191 : adjust rule for choosing no sw prefetch

@@ -434,10 +434,17 @@
     if (supports_lzcnt()) {
       if (FLAG_IS_DEFAULT(UseCountLeadingZerosInstruction)) {
         UseCountLeadingZerosInstruction = true;
       }
     }
+
+    // On family 21 processors default is no sw prefetch
+    if ( cpu_family() == 21 ) {
+      if (FLAG_IS_DEFAULT(AllocatePrefetchStyle)) {
+        AllocatePrefetchStyle = 0;
+      }
+    }
   }
 
   if( is_intel() ) { // Intel cpus specific settings
     if( FLAG_IS_DEFAULT(UseStoreImmI16) ) {
       UseStoreImmI16 = false; // don't use it on Intel cpus