CRIU time compensation required between checkpoint and restore (C/R)

[JasonFengJ9]

The elapsed time between C/R is indeterministic, any mechanism that might be affected by C/R elapsed time requires time compensation. A few changes have already been made for such time compensation.

• CRIU j9time_nano_time skips the elapsed time between Checkpoint/Restore #15016
• Add InternalCRIUSupport.getCheckpointRestoreTimeDelta() & tests #15112
• CRIU adjusts Object.wait/Thread.sleep/Unsafe.park #15499
• CRIU delay Thread.interrupt() in single thread mode #15648
• CRIU update TimerTask.nextExecutionTime with checkpointRestoreTimeDelta ibmruntimes/openj9-openjdk-jdk11#531 and those ported to other repos

Following are use scenarios that might require time compensations according to a recent code survey:

JVM natives might require time compensation

• TR_VerboseLog TR_Vlog_GPU for elapsed time measurement

  openj9/runtime/compiler/runtime/GPUHelpers.cpp

  Line 1542 in 62c6b5b

  TR_VerboseLog::writeLine(TR_Vlog_GPU, "\tcuLaunchKernel: %.3f msec.", (currentTime() - time)/1000);

• TR_VerboseLog for translationTime

   uint64_t translationStartTime = TR::Compiler->vm.getUSecClock();
   ...
   uint64_t translationTime = TR::Compiler->vm.getUSecClock() - translationStartTime;
   TR_VerboseLog::write(
                " time=%llu mem=%lluKB",
                translationTime,
  

• GC run finalization
  

  openj9/runtime/gc_base/FinalizerSupport.cpp

  Line 229 in 5a4ab53

  cycleIntervalWaitResult = omrthread_monitor_wait_timed(vm->finalizeMainMonitor, currentWaitTime, 0);

• -Xdump agent trigger with time measurement
  

  openj9/runtime/rastrace/trctrigger.c

  Line 1134 in 5a4ab53

  omrthread_sleep(UT_GLOBAL(sleepTimeMillis));

• JIT CpuUtilization::getCpuUtil
  

  openj9/runtime/compiler/env/CpuUtilization.cpp

  Lines 66 to 68 in 5a4ab53

  	// get CPU stats for the machine
  	portLibraryStatusSys = j9sysinfo_get_CPU_utilization(machineCpuStats);
  	portLibraryStatusVm = j9thread_get_process_times(vmCpuStats);

• OMR trace timeConversion

	spanPlatform = iterator->endPlatform - iterator->startPlatform;
	spanSystem = iterator->endSystem - iterator->startSystem;
	iterator->timeConversion = spanPlatform / spanSystem;

• GC statics _scavengerStats._scanCacheAllocationDurationDuringSavenger

	duration = omrtime_current_time_millis() - duration;
	env->_scavengerStats._scanCacheAllocationDurationDuringSavenger += duration;

Java APIs requiring time compensation