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Double the size of new frozen segments #76870

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merged 2 commits into from
Oct 11, 2022
Merged

Double the size of new frozen segments #76870

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353c503
Increase size of frozen segments linearly
EgorBo Oct 11, 2022
f7e98c9
Address feedback
EgorBo Oct 11, 2022
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41 changes: 28 additions & 13 deletions src/coreclr/vm/frozenobjectheap.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@
#include "common.h"
#include "frozenobjectheap.h"

// Size to reserve for a frozen segment
#define FOH_SEGMENT_SIZE (4 * 1024 * 1024)
// Default size to reserve for a frozen segment
#define FOH_SEGMENT_DEFAULT_SIZE (4 * 1024 * 1024)
// Size to commit on demand in that reserved space
#define FOH_COMMIT_SIZE (64 * 1024)

Expand Down Expand Up @@ -36,8 +36,6 @@ Object* FrozenObjectHeapManager::TryAllocateObject(PTR_MethodTable type, size_t

_ASSERT(type != nullptr);
_ASSERT(FOH_COMMIT_SIZE >= MIN_OBJECT_SIZE);
_ASSERT(FOH_SEGMENT_SIZE > FOH_COMMIT_SIZE);
_ASSERT(FOH_SEGMENT_SIZE % FOH_COMMIT_SIZE == 0);

// NOTE: objectSize is expected be the full size including header
_ASSERT(objectSize >= MIN_OBJECT_SIZE);
Expand All @@ -52,7 +50,7 @@ Object* FrozenObjectHeapManager::TryAllocateObject(PTR_MethodTable type, size_t
if (m_CurrentSegment == nullptr)
{
// Create the first segment on first allocation
m_CurrentSegment = new FrozenObjectSegment();
m_CurrentSegment = new FrozenObjectSegment(FOH_SEGMENT_DEFAULT_SIZE);
m_FrozenSegments.Append(m_CurrentSegment);
_ASSERT(m_CurrentSegment != nullptr);
}
Expand All @@ -63,7 +61,8 @@ Object* FrozenObjectHeapManager::TryAllocateObject(PTR_MethodTable type, size_t
// to create a new one
if (obj == nullptr)
{
m_CurrentSegment = new FrozenObjectSegment();
// Double the reserved size to reduce the number of frozen segments in apps with lots of frozen objects
m_CurrentSegment = new FrozenObjectSegment(m_CurrentSegment->GetSize() * 2);
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m_FrozenSegments.Append(m_CurrentSegment);

// Try again
Expand All @@ -77,17 +76,33 @@ Object* FrozenObjectHeapManager::TryAllocateObject(PTR_MethodTable type, size_t
}


FrozenObjectSegment::FrozenObjectSegment():
FrozenObjectSegment::FrozenObjectSegment(size_t size) :
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m_pStart(nullptr),
m_pCurrent(nullptr),
m_SizeCommitted(0),
m_Size(size),
m_SegmentHandle(nullptr)
COMMA_INDEBUG(m_ObjectsCount(0))
{
void* alloc = ClrVirtualAlloc(nullptr, FOH_SEGMENT_SIZE, MEM_RESERVE, PAGE_READWRITE);
_ASSERT(m_Size > FOH_COMMIT_SIZE);
_ASSERT(m_Size % FOH_COMMIT_SIZE == 0);

void* alloc = ClrVirtualAlloc(nullptr, m_Size, MEM_RESERVE, PAGE_READWRITE);
if (alloc == nullptr)
{
ThrowOutOfMemory();
// Try again with the default FOH size
if (m_Size > FOH_SEGMENT_DEFAULT_SIZE)
{
m_Size = FOH_SEGMENT_DEFAULT_SIZE;
_ASSERT(m_Size > FOH_COMMIT_SIZE);
_ASSERT(m_Size % FOH_COMMIT_SIZE == 0);
alloc = ClrVirtualAlloc(nullptr, m_Size, MEM_RESERVE, PAGE_READWRITE);
}

if (alloc == nullptr)
{
ThrowOutOfMemory();
}
}

// Commit a chunk in advance
Expand All @@ -107,7 +122,7 @@ FrozenObjectSegment::FrozenObjectSegment():
si.ibFirstObject = sizeof(ObjHeader);
si.ibAllocated = si.ibFirstObject;
si.ibCommit = FOH_COMMIT_SIZE;
si.ibReserved = FOH_SEGMENT_SIZE;
si.ibReserved = m_Size;

m_SegmentHandle = GCHeapUtilities::GetGCHeap()->RegisterFrozenSegment(&si);
if (m_SegmentHandle == nullptr)
Expand All @@ -125,13 +140,13 @@ FrozenObjectSegment::FrozenObjectSegment():

Object* FrozenObjectSegment::TryAllocateObject(PTR_MethodTable type, size_t objectSize)
{
_ASSERT(m_pStart != nullptr && FOH_SEGMENT_SIZE > 0 && m_SegmentHandle != nullptr); // Expected to be inited
_ASSERT(m_pStart != nullptr && m_Size > 0 && m_SegmentHandle != nullptr); // Expected to be inited
_ASSERT(IS_ALIGNED(m_pCurrent, DATA_ALIGNMENT));
_ASSERT(objectSize <= FOH_COMMIT_SIZE);
_ASSERT(m_pCurrent >= m_pStart + sizeof(ObjHeader));

const size_t spaceUsed = (size_t)(m_pCurrent - m_pStart);
const size_t spaceLeft = FOH_SEGMENT_SIZE - spaceUsed;
const size_t spaceLeft = m_Size - spaceUsed;

_ASSERT(spaceUsed >= sizeof(ObjHeader));
_ASSERT(spaceLeft >= sizeof(ObjHeader));
Expand All @@ -146,7 +161,7 @@ Object* FrozenObjectSegment::TryAllocateObject(PTR_MethodTable type, size_t obje
if (spaceUsed + objectSize + sizeof(ObjHeader) > m_SizeCommitted)
{
// Make sure we don't go out of bounds during this commit
_ASSERT(m_SizeCommitted + FOH_COMMIT_SIZE <= FOH_SEGMENT_SIZE);
_ASSERT(m_SizeCommitted + FOH_COMMIT_SIZE <= m_Size);

if (ClrVirtualAlloc(m_pStart + m_SizeCommitted, FOH_COMMIT_SIZE, MEM_COMMIT, PAGE_READWRITE) == nullptr)
{
Expand Down
10 changes: 9 additions & 1 deletion src/coreclr/vm/frozenobjectheap.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,9 +38,14 @@ class FrozenObjectHeapManager
class FrozenObjectSegment
{
public:
FrozenObjectSegment();
FrozenObjectSegment(size_t size);
Object* TryAllocateObject(PTR_MethodTable type, size_t objectSize);

size_t GetSize() const
{
return m_Size;
}

private:
// Start of the reserved memory, the first object starts at "m_pStart + sizeof(ObjHeader)" (its pMT)
uint8_t* m_pStart;
Expand All @@ -56,6 +61,9 @@ class FrozenObjectSegment
// m_SizeCommitted <= m_pStart + FOH_SIZE_RESERVED
size_t m_SizeCommitted;

// Total memory reserved for the current segment
size_t m_Size;

segment_handle m_SegmentHandle;
INDEBUG(size_t m_ObjectsCount);
};
Expand Down