[local gc] gc spinning part 1 (dotnet#17341)

Add an api so the VM can tell the GC how long to spin for to normalize across processor families.

Author: davmason

src/gc/gc.h

@@ -138,6 +138,8 @@ extern "C" uint32_t g_num_processors;
 
 extern VOLATILE(int32_t) g_fSuspensionPending;
 
+extern uint32_t g_yieldProcessorScalingFactor;
+
 ::IGCHandleManager*  CreateGCHandleManager();
 
 namespace WKS {

src/gc/gccommon.cpp

@@ -37,6 +37,8 @@ uint32_t* g_gc_card_table;
 
 VOLATILE(int32_t) g_fSuspensionPending = 0;
 
+uint32_t g_yieldProcessorScalingFactor = 1;
+
 #ifdef FEATURE_MANUALLY_MANAGED_CARD_BUNDLES
 uint32_t* g_gc_card_bundle_table;
 #endif

src/gc/gcee.cpp

@@ -615,6 +615,11 @@ void GCHeap::SetSuspensionPending(bool fSuspensionPending)
     }
 }
 
+void GCHeap::SetYieldProcessorScalingFactor(uint32_t yieldProcessorScalingFactor)
+{
+    g_yieldProcessorScalingFactor = yieldProcessorScalingFactor;
+}
+
 void GCHeap::ControlEvents(GCEventKeyword keyword, GCEventLevel level)
 {
     GCEventStatus::Set(GCEventProvider_Default, keyword, level);

src/gc/gcimpl.h

@@ -92,6 +92,8 @@ class GCHeap : public IGCHeapInternal
     bool RuntimeStructuresValid();
 
     void SetSuspensionPending(bool fSuspensionPending);
+    
+    void SetYieldProcessorScalingFactor(uint32_t yieldProcessorScalingFactor);
 
     void SetWaitForGCEvent();
     void ResetWaitForGCEvent();

src/gc/gcinterface.h

@@ -735,6 +735,9 @@ class IGCHeap {
     // Tells the GC when the VM is suspending threads.
     virtual void SetSuspensionPending(bool fSuspensionPending) = 0;
 
+    // Tells the GC how many YieldProcessor calls are equal to one scaled yield processor call.
+    virtual void SetYieldProcessorScalingFactor(uint32_t yieldProcessorScalingFactor) = 0;
+
     /*
     ============================================================================
     Add/RemoveMemoryPressure support routines. These are on the interface

src/gc/gcpriv.h

@@ -4346,3 +4346,13 @@ size_t gcard_of (uint8_t* object)
     return (size_t)(object) / card_size;
 }
 
+inline
+void YieldProcessorScalingFactor()
+{
+    unsigned int n = g_yieldProcessorScalingFactor;
+    _ASSERTE(n != 0);
+    do
+    {
+        YieldProcessor();
+    } while (--n != 0);
+}

src/vm/yieldprocessornormalized.cpp

@@ -92,6 +92,9 @@ static void InitializeYieldProcessorNormalized()
     g_yieldsPerNormalizedYield = yieldsPerNormalizedYield;
     g_optimalMaxNormalizedYieldsPerSpinIteration = optimalMaxNormalizedYieldsPerSpinIteration;
     s_isYieldProcessorNormalizedInitialized = true;
+
+
+    GCHeapUtilities::GetGCHeap()->SetYieldProcessorScalingFactor(yieldsPerNormalizedYield);
 }
 
 void EnsureYieldProcessorNormalizedInitialized()