Merge pull request eclipse-openj9#20725 from thallium/jfr-context-switch

Add JFR ThreadContextSwitchRate support

Author: tajila

runtime/oti/j9consts.h

@@ -951,6 +951,7 @@ extern "C" {
 #define J9JFR_EVENT_TYPE_CPU_LOAD 5
 #define J9JFR_EVENT_TYPE_THREAD_CPU_LOAD 6
 #define J9JFR_EVENT_TYPE_CLASS_LOADING_STATISTICS 7
+#define J9JFR_EVENT_TYPE_THREAD_CONTEXT_SWITCH_RATE 8
 
 /* JFR thread states */
 

runtime/oti/j9nonbuilder.h

@@ -440,6 +440,11 @@ typedef struct J9JFRClassLoadingStatistics {
 	I_64 unloadedClassCount;
 } J9JFRClassLoadingStatistics;
 
+typedef struct J9JFRThreadContextSwitchRate {
+	J9JFR_EVENT_COMMON_FIELDS
+	float switchRate;
+} J9JFRThreadContextSwitchRate;
+
 #endif /* defined(J9VM_OPT_JFR) */
 
 /* @ddr_namespace: map_to_type=J9CfrError */
@@ -5721,6 +5726,8 @@ typedef struct JFRState {
 	J9SysinfoCPUTime prevSysCPUTime;
 	omrthread_process_time_t prevProcCPUTimes;
 	int64_t prevProcTimestamp;
+	int64_t prevContextSwitchTimestamp;
+	uint64_t prevContextSwitches;
 } JFRState;
 
 typedef struct J9ReflectFunctionTable {

runtime/vm/JFRChunkWriter.cpp

@@ -888,4 +888,27 @@ VM_JFRChunkWriter::writeClassLoadingStatisticsEvent(void *anElement, void *userD
 	/* write size */
 	_bufferWriter->writeLEB128PaddedU32(dataStart, _bufferWriter->getCursor() - dataStart);
 }
+
+void
+VM_JFRChunkWriter::writeThreadContextSwitchRateEvent(void *anElement, void *userData)
+{
+	ThreadContextSwitchRateEntry *entry = (ThreadContextSwitchRateEntry *)anElement;
+	VM_BufferWriter *_bufferWriter = (VM_BufferWriter *)userData;
+
+	/* reserve size field */
+	U_8 *dataStart = _bufferWriter->getAndIncCursor(sizeof(U_32));
+
+	/* write event type */
+	_bufferWriter->writeLEB128(ThreadContextSwitchRateID);
+
+	/* write start time */
+	_bufferWriter->writeLEB128(entry->ticks);
+
+	/* write switch rate */
+	_bufferWriter->writeFloat(entry->switchRate);
+
+	/* write size */
+	_bufferWriter->writeLEB128PaddedU32(dataStart, (U_32)(_bufferWriter->getCursor() - dataStart));
+}
+
 #endif /* defined(J9VM_OPT_JFR) */

runtime/vm/JFRChunkWriter.hpp

@@ -74,6 +74,7 @@ enum MetadataTypeID {
 	CPUInformationID = 93,
 	CPULoadID = 95,
 	ThreadCPULoadID = 96,
+	ThreadContextSwitchRateID = 97,
 	ClassLoadingStatisticsID = 100,
 	PhysicalMemoryID = 108,
 	ExecutionSampleID = 109,
@@ -166,6 +167,7 @@ class VM_JFRChunkWriter {
 	static constexpr int THREAD_CPU_LOAD_EVENT_SIZE = (2 * sizeof(float)) + (4 * sizeof(I_64));
 	static constexpr int INITIAL_ENVIRONMENT_VARIABLE_EVENT_SIZE = 6000;
 	static constexpr int CLASS_LOADING_STATISTICS_EVENT_SIZE = 5 * sizeof(I_64);
+	static constexpr int THREAD_CONTEXT_SWITCH_RATE_SIZE = sizeof(float) + (3 * sizeof(I_64));
 
 	static constexpr int METADATA_ID = 1;
 
@@ -343,6 +345,8 @@ class VM_JFRChunkWriter {
 
 			pool_do(_constantPoolTypes.getClassLoadingStatisticsTable(), &writeClassLoadingStatisticsEvent, _bufferWriter);
 
+			pool_do(_constantPoolTypes.getThreadContextSwitchRateTable(), &writeThreadContextSwitchRateEvent, _bufferWriter);
+
 			/* Only write constant events in first chunk */
 			if (0 == _vm->jfrState.jfrChunkCount) {
 				writeJVMInformationEvent();
@@ -674,6 +678,8 @@ class VM_JFRChunkWriter {
 
 	static void writeClassLoadingStatisticsEvent(void *anElement, void *userData);
 
+	static void writeThreadContextSwitchRateEvent(void *anElement, void *userData);
+
 	UDATA
 	calculateRequiredBufferSize()
 	{
@@ -736,6 +742,8 @@ class VM_JFRChunkWriter {
 
 		requiredBufferSize += _constantPoolTypes.getClassLoadingStatisticsCount() * CLASS_LOADING_STATISTICS_EVENT_SIZE;
 
+		requiredBufferSize += _constantPoolTypes.getThreadContextSwitchRateCount() * THREAD_CONTEXT_SWITCH_RATE_SIZE;
+
 		return requiredBufferSize;
 	}
 

runtime/vm/JFRConstantPoolTypes.cpp

@@ -23,6 +23,7 @@
 #include "j9protos.h"
 #include "j9consts.h"
 #include "j9vmconstantpool.h"
+#include "pool_api.h"
 
 #if defined(J9VM_OPT_JFR)
 
@@ -1162,11 +1163,26 @@ VM_JFRConstantPoolTypes::addClassLoadingStatisticsEntry(J9JFRClassLoadingStatist
 
 	index = _classLoadingStatisticsCount;
 	_classLoadingStatisticsCount += 1;
-
 done:
 	return index;
 }
 
+void
+VM_JFRConstantPoolTypes::addThreadContextSwitchRateEntry(J9JFRThreadContextSwitchRate *threadContextSwitchRateData)
+{
+	ThreadContextSwitchRateEntry *entry = (ThreadContextSwitchRateEntry *)pool_newElement(_threadContextSwitchRateTable);
+
+	if (NULL == entry) {
+		_buildResult = OutOfMemory;
+		return;
+	}
+
+	entry->ticks = threadContextSwitchRateData->startTicks;
+	entry->switchRate = threadContextSwitchRateData->switchRate;
+
+	_threadContextSwitchRateCount += 1;
+}
+
 void
 VM_JFRConstantPoolTypes::printTables()
 {

runtime/vm/JFRConstantPoolTypes.hpp

@@ -234,6 +234,11 @@ struct ClassLoadingStatisticsEntry {
 	I_64 unloadedClassCount;
 };
 
+struct ThreadContextSwitchRateEntry {
+	I_64 ticks;
+	float switchRate;
+};
+
 struct JVMInformationEntry {
 	const char *jvmName;
 	const char *jvmVersion;
@@ -317,6 +322,8 @@ class VM_JFRConstantPoolTypes {
 	UDATA _threadCPULoadCount;
 	J9Pool *_classLoadingStatisticsTable;
 	UDATA _classLoadingStatisticsCount;
+	J9Pool *_threadContextSwitchRateTable;
+	U_32 _threadContextSwitchRateCount;
 
 	/* Processing buffers */
 	StackFrame *_currentStackFrameBuffer;
@@ -586,6 +593,8 @@ class VM_JFRConstantPoolTypes {
 
 	U_32 addClassLoadingStatisticsEntry(J9JFRClassLoadingStatistics *classLoadingStatisticsData);
 
+	void addThreadContextSwitchRateEntry(J9JFRThreadContextSwitchRate *threadContextSwitchRateData);
+
 	J9Pool *getExecutionSampleTable()
 	{
 		return _executionSampleTable;
@@ -626,6 +635,11 @@ class VM_JFRConstantPoolTypes {
 		return _classLoadingStatisticsTable;
 	}
 
+	J9Pool *getThreadContextSwitchRateTable()
+	{
+		return _threadContextSwitchRateTable;
+	}
+
 	UDATA getExecutionSampleCount()
 	{
 		return _executionSampleCount;
@@ -666,6 +680,11 @@ class VM_JFRConstantPoolTypes {
 		return _classLoadingStatisticsCount;
 	}
 
+	U_32 getThreadContextSwitchRateCount()
+	{
+		return _threadContextSwitchRateCount;
+	}
+
 	ClassloaderEntry *getClassloaderEntry()
 	{
 		return _firstClassloaderEntry;
@@ -818,6 +837,9 @@ class VM_JFRConstantPoolTypes {
 			case J9JFR_EVENT_TYPE_CLASS_LOADING_STATISTICS:
 				addClassLoadingStatisticsEntry((J9JFRClassLoadingStatistics *)event);
 				break;
+			case J9JFR_EVENT_TYPE_THREAD_CONTEXT_SWITCH_RATE:
+				addThreadContextSwitchRateEntry((J9JFRThreadContextSwitchRate *)event);
+				break;
 			default:
 				Assert_VM_unreachable();
 				break;
@@ -1146,6 +1168,8 @@ class VM_JFRConstantPoolTypes {
 		, _threadCPULoadCount(0)
 		, _classLoadingStatisticsTable(NULL)
 		, _classLoadingStatisticsCount(0)
+		, _threadContextSwitchRateTable(NULL)
+		, _threadContextSwitchRateCount(0)
 		, _previousStackTraceEntry(NULL)
 		, _firstStackTraceEntry(NULL)
 		, _previousThreadEntry(NULL)
@@ -1266,6 +1290,12 @@ class VM_JFRConstantPoolTypes {
 			goto done;
 		}
 
+		_threadContextSwitchRateTable = pool_new(sizeof(ThreadContextSwitchRateEntry), 0, sizeof(U_64), 0, J9_GET_CALLSITE(), OMRMEM_CATEGORY_VM, POOL_FOR_PORT(privatePortLibrary));
+		if (NULL == _threadContextSwitchRateTable ) {
+			_buildResult = OutOfMemory;
+			goto done;
+		}
+
 		/* Add reserved index for default entries. For strings zero is the empty or NUll string.
 		 * For package zero is the deafult package, for Module zero is the unnamed module. ThreadGroup
 		 * zero is NULL threadGroup.
@@ -1355,6 +1385,7 @@ class VM_JFRConstantPoolTypes {
 		pool_kill(_cpuLoadTable);
 		pool_kill(_threadCPULoadTable);
 		pool_kill(_classLoadingStatisticsTable);
+		pool_kill(_threadContextSwitchRateTable);
 		j9mem_free_memory(_globalStringTable);
 	}
 

runtime/vm/jfr.cpp

@@ -96,6 +96,9 @@ jfrEventSize(J9JFREvent *jfrEvent)
 	case J9JFR_EVENT_TYPE_CLASS_LOADING_STATISTICS:
 		size = sizeof(J9JFRClassLoadingStatistics);
 		break;
+	case J9JFR_EVENT_TYPE_THREAD_CONTEXT_SWITCH_RATE:
+		size = sizeof(J9JFRThreadContextSwitchRate);
+		break;
 	default:
 		Assert_VM_unreachable();
 		break;
@@ -720,6 +723,7 @@ initializeJFR(J9JavaVM *vm, BOOLEAN lateInit)
 
 	vm->jfrState.prevSysCPUTime.timestamp = -1;
 	vm->jfrState.prevProcTimestamp = -1;
+	vm->jfrState.prevContextSwitchTimestamp = -1;
 	if (omrthread_monitor_init_with_name(&vm->jfrBufferMutex, 0, "JFR global buffer mutex")) {
 		goto fail;
 	}
@@ -995,6 +999,35 @@ jfrClassLoadingStatistics(J9VMThread *currentThread)
 	}
 }
 
+void
+jfrThreadContextSwitchRate(J9VMThread *currentThread)
+{
+	PORT_ACCESS_FROM_VMC(currentThread);
+	OMRPORT_ACCESS_FROM_J9PORT(PORTLIB);
+
+	uint64_t switches = 0;
+	int32_t rc = omrsysinfo_get_number_context_switches(&switches);
+
+	if (0 == rc) {
+		J9JFRThreadContextSwitchRate *jfrEvent = (J9JFRThreadContextSwitchRate *)reserveBuffer(currentThread, sizeof(J9JFRThreadContextSwitchRate));
+		if (NULL != jfrEvent) {
+			JFRState *jfrState = &currentThread->javaVM->jfrState;
+			int64_t currentTime = j9time_nano_time();
+
+			initializeEventFields(currentThread, (J9JFREvent *)jfrEvent, J9JFR_EVENT_TYPE_THREAD_CONTEXT_SWITCH_RATE);
+
+			if (-1 == jfrState->prevContextSwitchTimestamp) {
+				jfrEvent->switchRate = 0;
+			} else {
+				int64_t timeDelta = currentTime - jfrState->prevContextSwitchTimestamp;
+				jfrEvent->switchRate = ((double)(switches - jfrState->prevContextSwitches) / timeDelta) * 1e9;
+			}
+			jfrState->prevContextSwitches = switches;
+			jfrState->prevContextSwitchTimestamp = currentTime;
+		}
+	}
+}
+
 static int J9THREAD_PROC
 jfrSamplingThreadProc(void *entryArg)
 {
@@ -1013,11 +1046,12 @@ jfrSamplingThreadProc(void *entryArg)
 				internalAcquireVMAccess(currentThread);
 				jfrCPULoad(currentThread);
 				jfrClassLoadingStatistics(currentThread);
-				internalReleaseVMAccess(currentThread);
-				omrthread_monitor_enter(vm->jfrSamplerMutex);
 				if (0 == (count % 1000)) { // 10 seconds
 					J9SignalAsyncEvent(vm, NULL, vm->jfrThreadCPULoadAsyncKey);
+					jfrThreadContextSwitchRate(currentThread);
 				}
+				internalReleaseVMAccess(currentThread);
+				omrthread_monitor_enter(vm->jfrSamplerMutex);
 			}
 			count += 1;
 			omrthread_monitor_wait_timed(vm->jfrSamplerMutex, J9JFR_SAMPLING_RATE, 0);