protected override void PreGC(int generation)
{
try {
// Take ownership of the buffer to prevent mutating threads from
// interleaving with us.
DebugStub.Assert(Buffer.OwningThread == null);
Buffer.OwningThread = Thread.CurrentThread;
Buffer.LogTick();
if (generation >= maxGeneration)
{
generation = maxGeneration - 1;
}
generations[generation]++;
unsafe
{
fixed(int *ptr = &generations[0])
{
ProfilerBuffer.LogGenerations(maxGeneration, ptr);
}
}
}
catch (Exception) {
enabled = false;
throw;
}
}
// The rest of our implementation details:
private uint GetStackId(Type type, UIntPtr size, UIntPtr[] stackEips, uint stackSize)
{
// First make sure that we have a type record for the object being
// instantiated at this stack.
uint typeNo = GetTypeId(type);
DebugStub.Assert(stackSize <= stackEips.Length);
// Then, make sure we have a function record for each Eip in the stack. Of course
// we don't know when a bunch of Eips map to different offsets in the same function.
// So make a function for each unique Eip & fix it up in the post-processing.
// Hopefully there aren't too many unique callsites in each method.
ulong hash = typeNo; // perhaps "typeNo ^ size" ?
for (int i = 0; i < stackSize; i++)
{
// Map the individual Eips into their corresponding functions
stackNos[i] = GetFunctionId(stackEips[i]);
hash = (hash << 11) + (hash ^ stackNos[i]);
}
// TODO: Note that we will statistically map some distinct stacks into the same
// stack if they have the same hash.
object o = stackTable[hash];
if (o != null)
{
return((uint)o);
}
// It's a novel stack. Note that we embed the size into the stack, but we
// don't include the size in the hash. There's a technique for sharing
// prefixes of stacks that could be explored here to get more accurate profiles
// without huge stack expansion.
// TODO: consider the above.
uint stackNo = nextStackNo++;
// Stacks are emitted backwards, presumably to support common prefixes better.
for (int i = (int)stackSize - 1; i >= 0; i--)
{
functionsIDs[stackSize - 1 - i] = stackNos[i];
}
unsafe
{
fixed(uint *ptr = &functionsIDs[0])
{
ProfilerBuffer.LogStack(stackNo, typeNo, size, stackSize, ptr);
}
}
stackTable[hash] = stackNo;
return(stackNo);
}
// We are finished scanning one object
protected override void EndScanOneObject()
{
unsafe
{
fixed(UIntPtr *ptr = &tempGCBuffer[0])
{
ProfilerBuffer.LogObject(tempGCBufferEntries, ptr);
tempGCBufferEntries = 0;
}
}
}
//
// Local definitions
//
public void LogTick()
{
// Log an entry describing the delta in cycles
ulong nowCycle = Processor.CycleCount;
// Emit a tick-count record only if it's been a while since the last one.
if (nowCycle > lastCycle + cycleGranularity)
{
lastCycle = nowCycle;
ProfilerBuffer.LogInterval((ulong)((lastCycle - firstCycle) / 1000000));
}
}
// Initialization, prior to attempting to set this profiler into the GC. It's
// inappropriate to do this stuff inside a constructor.
internal void Initialize(ulong Size, ulong Flags)
{
options = Flags;
typeTable = new Hashtable();
stackTable = new Hashtable();
funcTable = new Hashtable();
stackEips = new UIntPtr[stackSize];
stackNos = new uint[stackSize];
generations = new int[maxGeneration];
functionsIDs = new uint[stackSize];
Buffer = new ProfilerBuffer();
tempGCBuffer = new UIntPtr[tempBufferSize];
tempGCBufferEntries = 0;
#if LEGACY_GCTRACING
bufferSize = Size;
unsafe {
// Allocate the memory indicated as parameter, as nonGC
#if SINGULARITY_KERNEL
UIntPtr pages = Microsoft.Singularity.Memory.MemoryManager.PagesFromBytes(bufferSize);
bufferMemory = (byte *)Microsoft.Singularity.Memory.MemoryManager.KernelAllocate(
pages, null, 0, System.GCs.PageType.NonGC).ToPointer();
#else // !SINGULARITY_KERNEL
bufferMemory = (byte *)PageTableService.Allocate(bufferSize);
#endif //SINGULARITY_KERNEL
if (bufferMemory != null)
{
// When we set this, we are no longer single-threaded:
ProfilerBuffer.SetupBuffer(bufferMemory, bufferSize);
this.enabled = true;
}
}
#else // LEGACY_GCTRACING
typeSource = GCTypeSource.Create("GC.TypeDefinitions", (uint)Size, options);
EventSource = GCEventSource.Create("GC.Events", (uint)Size, options);
if ((typeSource == null) || (EventSource == null))
{
typeSource = null;
EventSource = null;
this.enabled = false;
}
else
{
TypeStorageHandle = typeSource.Storage.GetHandle();
StorageHandle = EventSource.Storage.GetHandle();
this.enabled = true;
}
#endif // LEGACY_GCTRACING
}
private uint GetFunctionId(UIntPtr eip)
{
// Given the EIP of a Function, make sure the function has been defined. Since we
// don't have enough runtime information to map Eips to functions, we must rely on
// post-processing.
object o = funcTable[eip];
if (o != null)
{
return((uint)o);
}
uint funcNo = nextFuncNo++;
ProfilerBuffer.LogFunction(funcNo, eip);
funcTable[eip] = funcNo;
return(funcNo);
}
private uint GetTypeId(Type type)
{
// Given a Type, make sure that it has been defined.
object o = typeTable[type];
if (o != null)
{
return((uint)o);
}
uint typeNo = nextTypeNo++;
// Log this entry before putting it into the hashtable, where other threads might
// see it. This means we may have duplicate conflicting entries for the same logical
// type, but this is tolerated by the profiler.
ProfilerBuffer.LogType(typeNo, type.FullName);
typeTable[type] = typeNo;
return(typeNo);
}
// In the list of roots, we have found another object
protected override void ScanOneRoot(UIntPtr objectAddress)
{
if (objectAddress != 0)
{
//
// If we filled in the temporary buffer, log it and resume
// from the beginning.
if (tempGCBufferEntries >= tempBufferSize)
{
unsafe
{
fixed(UIntPtr *ptr = &tempGCBuffer[0])
{
ProfilerBuffer.LogRoots(tempGCBufferEntries, ptr);
tempGCBufferEntries = 0;
}
}
}
tempGCBuffer[tempGCBufferEntries++] = (UIntPtr)objectAddress;
}
}
// Create a log entry for the allocation that just occurred on this thread.
protected override void Allocation(UIntPtr objAddr, Type type, UIntPtr size)
{
bool iflag;
// We cannot recurse inside an Allocation notification, or we will simply
// blow the stack on the first entry. Also, we don't want to log allocations
// that occur as a consequence of logging the state of the GC heap -- though
// we could support that if we chose to.
if (enabled &&
recurseThread != Thread.CurrentThread && // recurse?
Buffer.OwningThread != Thread.CurrentThread) // GC logging?
{
iflag = Processor.DisableLocalPreemption();
allocationLock.Acquire();
try {
DebugStub.Assert(recurseThread == null);
recurseThread = Thread.CurrentThread;
Buffer.LogTick();
uint stackSize = Isa.GetStackReturnAddresses(stackEips);
uint stkNo = 0;
if (stackSize > 0)
{
stkNo = GetStackId(type, size, stackEips, stackSize);
}
ProfilerBuffer.LogAllocation(Thread.CurrentThread.GetThreadId(), objAddr, stkNo);
}
finally {
recurseThread = null;
allocationLock.Release();
Processor.RestoreLocalPreemption(iflag);
}
}
}
// A GC has finished. The world is in a sane place, except that we might not
// have started up all the mutator threads if this is a StopTheWorld collection.
protected override void PostGC()
{
try {
// emit the fact a GC has happened, including the state of the heap.
// TODO: have another function to log the tick count here to estimate the
// time spent in GC too.
Buffer.LogTick();
// We should have an empty buffer, meaning we completed logging from the
// previous operation while entering this code.
DebugStub.Assert(tempGCBufferEntries == 0);
ScanRoots();
unsafe
{
fixed(UIntPtr *ptr = &tempGCBuffer[0])
{
ProfilerBuffer.LogRoots(tempGCBufferEntries, ptr);
tempGCBufferEntries = 0;
}
}
// Write all the reachability graph of the heap
ScanObjects();
// Once we have finished writing everything, we can allow mutator threads to
// share access to the fileBuffer with their own consistent entries.
DebugStub.Assert(Buffer.OwningThread == Thread.CurrentThread);
Buffer.OwningThread = null;
}
catch (Exception) {
enabled = false;
throw;
}
}