Ergonomics Profile

src/hotspot/share/gc/shared/gcConfig.cpp

@@ -95,7 +95,7 @@ void GCConfig::fail_if_non_included_gc_is_selected() {
   NOT_ZGC(         FAIL_IF_SELECTED(UseZGC));
 }
 
-void GCConfig::select_gc_ergonomically() {
+void select_gc_ergonomically_shared() {
   if (os::is_server_class_machine()) {
 #if INCLUDE_G1GC
     FLAG_SET_ERGO_IF_DEFAULT(UseG1GC, true);
@@ -111,6 +111,38 @@ void GCConfig::select_gc_ergonomically() {
   }
 }
 
+void select_gc_ergonomically_dedicated() {
+  julong phys_mem = os::physical_memory();
+  if (os::active_processor_count() <= 1) {
+#if INCLUDE_SERIALGC
+      FLAG_SET_ERGO_IF_DEFAULT(UseSerialGC, true);
+#endif
+    } else if (phys_mem >= 16*G) {
+#if INCLUDE_ZGC
+      FLAG_SET_ERGO_IF_DEFAULT(UseZGC, true);
+#endif
+    } else if (phys_mem > 2048*M) {
+#if INCLUDE_G1GC
+      FLAG_SET_ERGO_IF_DEFAULT(UseG1GC, true);
+#endif
+    } else { 
+#if INCLUDE_PARALLELGC
+      FLAG_SET_ERGO_IF_DEFAULT(UseParallelGC, true);
+#endif
+    }
+}
+
+void GCConfig::select_gc_ergonomically() {
+  if (strcmp(ErgonomicsProfile, "shared") == 0) {
+    select_gc_ergonomically_shared();
+  } else if (strcmp(ErgonomicsProfile, "dedicated") == 0) {
+    select_gc_ergonomically_dedicated();
+  } else {
+    // We have got to have at least one GC selected. Otherwise, we will crash.
+    ShouldNotReachHere();
+  }
+}
+
 bool GCConfig::is_no_gc_selected() {
   FOR_EACH_INCLUDED_GC(gc) {
     if (gc->_flag) {

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

@@ -131,6 +131,12 @@
   product(bool, UseShenandoahGC, false,                                     \
           "Use the Shenandoah garbage collector")                           \
                                                                             \
+  product(ccstr, ErgonomicsProfile, "shared",                               \
+          "Ergonomics profile to use. "                                     \
+          "\"shared\" (default) for when the JVM is running "         \
+          "in a traditional environment and \"dedicated\" for when the "         \
+          "JVM is running on an environment such as containers")            \
+                                                                            \
   /* notice: the max range value here is INT_MAX not UINT_MAX  */           \
   /* to protect from overflows                                 */           \
   product(uint, ParallelGCThreads, 0,                                       \

src/hotspot/share/runtime/arguments.cpp

@@ -70,6 +70,9 @@
 #if INCLUDE_JFR
 #include "jfr/jfr.hpp"
 #endif
+#ifdef LINUX
+#include "osContainer_linux.hpp"
+#endif
 
 #include <limits>
 
@@ -1487,6 +1490,12 @@ void Arguments::set_use_compressed_klass_ptrs() {
 #endif // _LP64
 }
 
+static void validate_ergonomics_profile() {
+  if (strcmp(ErgonomicsProfile, "shared") != 0 && strcmp(ErgonomicsProfile, "dedicated") != 0) {
+    vm_exit_during_initialization(err_msg("Unsupported ErgonomicsProfile: %s", ErgonomicsProfile));
+  }
+}
+
 void Arguments::set_conservative_max_heap_alignment() {
   // The conservative maximum required alignment for the heap is the maximum of
   // the alignments imposed by several sources: any requirements from the heap
@@ -1514,6 +1523,21 @@ jint Arguments::set_ergonomics_flags() {
   return JNI_OK;
 }
 
+void Arguments::set_ergonomics_profile() {
+  validate_ergonomics_profile();
+
+  if (FLAG_IS_DEFAULT(ErgonomicsProfile)){
+#ifdef LINUX
+    if (OSContainer::is_containerized()){
+      FLAG_SET_ERGO(ErgonomicsProfile, "dedicated");
+    }
+#endif //LINUX
+  }
+
+  // Store so we can expose through JMX RuntimeMBean
+  PropertyList_add(&_system_properties, new SystemProperty("java.vm.ergonomics.profile", ErgonomicsProfile,  false));
+}
+
 size_t Arguments::limit_heap_by_allocatable_memory(size_t limit) {
   size_t max_allocatable;
   size_t result = limit;
@@ -1561,6 +1585,21 @@ void Arguments::set_heap_size() {
                                        : (julong)MaxRAM;
   }
 
+  // Update default heap size for dedicated ergonomics profile
+  if (strcmp(ErgonomicsProfile, "dedicated") == 0) {
+    FLAG_SET_DEFAULT(InitialRAMPercentage, 50.0);
+    if (phys_mem >= 16*G){
+      FLAG_SET_DEFAULT(MaxRAMPercentage, 90.0); 
+    } else if (phys_mem >= 6*G){
+      FLAG_SET_DEFAULT(MaxRAMPercentage, 85.0);
+    } else if (phys_mem >= 4*G){
+      FLAG_SET_DEFAULT(MaxRAMPercentage, 80.0);
+    } else if (phys_mem >= 0.5*G){
+      FLAG_SET_DEFAULT(MaxRAMPercentage, 75.0);
+    } else { 
+      FLAG_SET_DEFAULT(MaxRAMPercentage, 50.0);
+    }
+  }
 
   // Convert deprecated flags
   if (FLAG_IS_DEFAULT(MaxRAMPercentage) &&
@@ -3977,6 +4016,9 @@ jint Arguments::parse(const JavaVMInitArgs* initial_cmd_args) {
 }
 
 jint Arguments::apply_ergo() {
+  // Set the ergonomics profile
+  set_ergonomics_profile();
+
   // Set flags based on ergonomics.
   jint result = set_ergonomics_flags();
   if (result != JNI_OK) return result;

src/hotspot/share/runtime/arguments.hpp

@@ -260,6 +260,7 @@ class Arguments : AllStatic {
   static bool _ClipInlining;
 
   // GC ergonomics
+  static void set_ergonomics_profile();
   static void set_conservative_max_heap_alignment();
   static void set_use_compressed_oops();
   static void set_use_compressed_klass_ptrs();

src/java.management/share/classes/java/lang/management/RuntimeMXBean.java

@@ -359,4 +359,17 @@ public default long getPid() {
      *     to the system properties.
      */
     public java.util.Map<String, String> getSystemProperties();
+
+    /**
+     * Returns the selected ergonomics profile for this Java virtual machine.
+     * The profile will be one of the following:
+     * <ul>
+     *   <li>shared</li>
+     *   <li>dedicated</li>
+     * </ul>
+     * 
+     * @return the name of the selected ergonomics profile
+     */
+    public String getJvmErgonomicsProfile();
+
 }

src/java.management/share/classes/sun/management/RuntimeImpl.java

@@ -133,6 +133,10 @@ public Map<String,String> getSystemProperties() {
         return map;
     }
 
+    public String getJvmErgonomicsProfile() {
+        return jvm.getErgonomicsProfile();
+    }
+
     public ObjectName getObjectName() {
         return Util.newObjectName(ManagementFactory.RUNTIME_MXBEAN_NAME);
     }

src/java.management/share/classes/sun/management/VMManagement.java

@@ -73,6 +73,7 @@ public interface VMManagement {
     public long    getStartupTime();
     public long    getUptime();
     public int     getAvailableProcessors();
+    public String  getErgonomicsProfile();
 
     // Compilation Subsystem
     public String  getCompilerName();

src/java.management/share/classes/sun/management/VMManagementImpl.java

@@ -33,6 +33,7 @@
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.List;
+
 import java.util.Arrays;
 import java.util.Collections;
 import java.security.AccessController;
@@ -201,6 +202,10 @@ public synchronized List<String> getVmArguments() {
     private native long getUptime0();
     public native int getAvailableProcessors();
 
+    public String getErgonomicsProfile() {
+        return System.getProperty("java.vm.ergonomics.profile");
+    }
+
     // Compilation Subsystem
     public String   getCompilerName() {
         @SuppressWarnings("removal")