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-rw-r--r--src/qml/memory/qv4mm.cpp110
1 files changed, 92 insertions, 18 deletions
diff --git a/src/qml/memory/qv4mm.cpp b/src/qml/memory/qv4mm.cpp
index 7c57b93d9b..64b07153cc 100644
--- a/src/qml/memory/qv4mm.cpp
+++ b/src/qml/memory/qv4mm.cpp
@@ -165,6 +165,13 @@ struct MemorySegment {
size_t pageSize = WTF::pageSize();
size = (size + pageSize - 1) & ~(pageSize - 1);
+#if !defined(Q_OS_LINUX) && !defined(Q_OS_WIN)
+ // Linux and Windows zero out pages that have been decommitted and get committed again.
+ // unfortunately that's not true on other OSes (e.g. BSD based ones), so zero out the
+ // memory before decommit, so that we can be sure that all chunks we allocate will be
+ // zero initialized.
+ memset(chunk, 0, size);
+#endif
pageReservation.decommit(chunk, size);
}
@@ -259,6 +266,18 @@ void ChunkAllocator::free(Chunk *chunk, size_t size)
Q_ASSERT(false);
}
+#ifdef DUMP_SWEEP
+QString binary(quintptr n) {
+ QString s = QString::number(n, 2);
+ while (s.length() < 64)
+ s.prepend(QChar::fromLatin1('0'));
+ return s;
+}
+#define SDUMP qDebug
+#else
+QString binary(quintptr) { return QString(); }
+#define SDUMP if (1) ; else qDebug
+#endif
void Heap::Base::markChildren(MarkStack *markStack)
{
@@ -318,11 +337,22 @@ void Heap::Base::markChildren(MarkStack *markStack)
}
}
+// Stores a classname -> freed count mapping.
+typedef QHash<const char*, int> MMStatsHash;
+Q_GLOBAL_STATIC(MMStatsHash, freedObjectStatsGlobal)
-void Chunk::sweep()
+// This indirection avoids sticking QHash code in each of the call sites, which
+// shaves off some instructions in the case that it's unused.
+static void increaseFreedCountForClass(const char *className)
{
- // DEBUG << "sweeping chunk" << this << (*freeList);
+ (*freedObjectStatsGlobal())[className]++;
+}
+
+void Chunk::sweep(ClassDestroyStatsCallback classCountPtr)
+{
+ SDUMP() << "sweeping chunk" << this;
HeapItem *o = realBase();
+ bool lastSlotFree = false;
for (uint i = 0; i < Chunk::EntriesInBitmap; ++i) {
#if WRITEBARRIER(none)
Q_ASSERT((grayBitmap[i] | blackBitmap[i]) == blackBitmap[i]); // check that we don't have gray only objects
@@ -330,7 +360,13 @@ void Chunk::sweep()
quintptr toFree = objectBitmap[i] ^ blackBitmap[i];
Q_ASSERT((toFree & objectBitmap[i]) == toFree); // check all black objects are marked as being used
quintptr e = extendsBitmap[i];
- // DEBUG << hex << " index=" << i << toFree;
+ SDUMP() << " index=" << i;
+ SDUMP() << " toFree =" << binary(toFree);
+ SDUMP() << " black =" << binary(blackBitmap[i]);
+ SDUMP() << " object =" << binary(objectBitmap[i]);
+ SDUMP() << " extends =" << binary(e);
+ if (lastSlotFree)
+ e &= (e + 1); // clear all lowest extent bits
while (toFree) {
uint index = qCountTrailingZeroBits(toFree);
quintptr bit = (static_cast<quintptr>(1) << index);
@@ -349,14 +385,21 @@ void Chunk::sweep()
HeapItem *itemToFree = o + index;
Heap::Base *b = *itemToFree;
- if (b->vtable()->destroy) {
- b->vtable()->destroy(b);
+ const VTable *v = b->vtable();
+ if (Q_UNLIKELY(classCountPtr))
+ classCountPtr(v->className);
+ if (v->destroy) {
+ v->destroy(b);
b->_checkIsDestroyed();
}
}
objectBitmap[i] = blackBitmap[i];
grayBitmap[i] = 0;
extendsBitmap[i] = e;
+ lastSlotFree = !((objectBitmap[i]|extendsBitmap[i]) >> (sizeof(quintptr)*8 - 1));
+ SDUMP() << " new extends =" << binary(e);
+ SDUMP() << " lastSlotFree" << lastSlotFree;
+ Q_ASSERT((objectBitmap[i] & extendsBitmap[i]) == 0);
o += Chunk::Bits;
}
// DEBUG << "swept chunk" << this << "freed" << slotsFreed << "slots.";
@@ -649,7 +692,7 @@ done:
return m;
}
-void BlockAllocator::sweep()
+void BlockAllocator::sweep(ClassDestroyStatsCallback classCountPtr)
{
nextFree = 0;
nFree = 0;
@@ -658,7 +701,7 @@ void BlockAllocator::sweep()
// qDebug() << "BlockAlloc: sweep";
usedSlotsAfterLastSweep = 0;
for (auto c : chunks) {
- c->sweep();
+ c->sweep(classCountPtr);
c->sortIntoBins(freeBins, NumBins);
// qDebug() << "used slots in chunk" << c << ":" << c->nUsedSlots();
usedSlotsAfterLastSweep += c->nUsedSlots();
@@ -724,22 +767,27 @@ HeapItem *HugeItemAllocator::allocate(size_t size) {
return c->first();
}
-static void freeHugeChunk(ChunkAllocator *chunkAllocator, const HugeItemAllocator::HugeChunk &c)
+static void freeHugeChunk(ChunkAllocator *chunkAllocator, const HugeItemAllocator::HugeChunk &c, ClassDestroyStatsCallback classCountPtr)
{
HeapItem *itemToFree = c.chunk->first();
Heap::Base *b = *itemToFree;
- if (b->vtable()->destroy) {
- b->vtable()->destroy(b);
+ const VTable *v = b->vtable();
+ if (Q_UNLIKELY(classCountPtr))
+ classCountPtr(v->className);
+
+ if (v->destroy) {
+ v->destroy(b);
b->_checkIsDestroyed();
}
chunkAllocator->free(c.chunk, c.size);
}
-void HugeItemAllocator::sweep() {
- auto isBlack = [this] (const HugeChunk &c) {
+void HugeItemAllocator::sweep(ClassDestroyStatsCallback classCountPtr)
+{
+ auto isBlack = [this, classCountPtr] (const HugeChunk &c) {
bool b = c.chunk->first()->isBlack();
if (!b)
- freeHugeChunk(chunkAllocator, c);
+ freeHugeChunk(chunkAllocator, c, classCountPtr);
return !b;
};
@@ -768,7 +816,7 @@ void HugeItemAllocator::collectGrayItems(MarkStack *markStack)
void HugeItemAllocator::freeAll()
{
for (auto &c : chunks) {
- freeHugeChunk(chunkAllocator, c);
+ freeHugeChunk(chunkAllocator, c, nullptr);
}
}
@@ -984,7 +1032,7 @@ void MemoryManager::mark()
markStack.drain();
}
-void MemoryManager::sweep(bool lastSweep)
+void MemoryManager::sweep(bool lastSweep, ClassDestroyStatsCallback classCountPtr)
{
for (PersistentValueStorage::Iterator it = m_weakValues->begin(); it != m_weakValues->end(); ++it) {
Managed *m = (*it).managed();
@@ -1031,8 +1079,8 @@ void MemoryManager::sweep(bool lastSweep)
}
}
- blockAllocator.sweep();
- hugeItemAllocator.sweep();
+ blockAllocator.sweep(classCountPtr);
+ hugeItemAllocator.sweep(classCountPtr);
}
bool MemoryManager::shouldRunGC() const
@@ -1059,6 +1107,13 @@ size_t dumpBins(BlockAllocator *b, bool printOutput = true)
if (printOutput)
qDebug() << " number of entries in slot" << i << ":" << nEntries;
}
+ SDUMP() << " large slot map";
+ HeapItem *h = b->freeBins[BlockAllocator::NumBins - 1];
+ while (h) {
+ SDUMP() << " " << hex << (quintptr(h)/32) << h->freeData.availableSlots;
+ h = h->freeData.next;
+ }
+
if (printOutput)
qDebug() << " total mem in bins" << totalSlotMem*Chunk::SlotSize;
return totalSlotMem*Chunk::SlotSize;
@@ -1105,7 +1160,7 @@ void MemoryManager::runGC()
mark();
qint64 markTime = t.nsecsElapsed()/1000;
t.restart();
- sweep();
+ sweep(false, increaseFreedCountForClass);
const size_t usedAfter = getUsedMem();
const size_t largeItemsAfter = getLargeItemsMem();
qint64 sweepTime = t.nsecsElapsed()/1000;
@@ -1120,6 +1175,20 @@ void MemoryManager::runGC()
qDebug() << "Marked object in" << markTime << "us.";
qDebug() << " " << markStackSize << "objects marked";
qDebug() << "Sweeped object in" << sweepTime << "us.";
+
+ // sort our object types by number of freed instances
+ MMStatsHash freedObjectStats;
+ std::swap(freedObjectStats, *freedObjectStatsGlobal());
+ typedef std::pair<const char*, int> ObjectStatInfo;
+ std::vector<ObjectStatInfo> freedObjectsSorted;
+ freedObjectsSorted.reserve(freedObjectStats.count());
+ for (auto it = freedObjectStats.constBegin(); it != freedObjectStats.constEnd(); ++it) {
+ freedObjectsSorted.push_back(std::make_pair(it.key(), it.value()));
+ }
+ std::sort(freedObjectsSorted.begin(), freedObjectsSorted.end(), [](const ObjectStatInfo &a, const ObjectStatInfo &b) {
+ return a.second > b.second && strcmp(a.first, b.first) < 0;
+ });
+
qDebug() << "Used memory before GC:" << usedBefore;
qDebug() << "Used memory after GC :" << usedAfter;
qDebug() << "Freed up bytes :" << (usedBefore - usedAfter);
@@ -1131,6 +1200,11 @@ void MemoryManager::runGC()
qDebug() << "Large item memory after GC:" << largeItemsAfter;
qDebug() << "Large item memory freed up:" << (largeItemsBefore - largeItemsAfter);
}
+
+ for (auto it = freedObjectsSorted.cbegin(); it != freedObjectsSorted.cend(); ++it) {
+ qDebug().noquote() << QString::fromLatin1("Freed JS type: %1 (%2 instances)").arg(QString::fromLatin1(it->first), QString::number(it->second));
+ }
+
qDebug() << "======== End GC ========";
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-23 14:07:26 +0000