/**
* Walk all segments and calculate the maximum number of chunks needed to represent the current heap.
* The chunk calculation is done on a per segment basis (no segment can represent memory from more than 1 chunk),
* and partial sized chunks (ie: less than the chunk size) are reserved for any remaining space at the end of a
* segment.
* @return number of chunks required to represent the current heap memory.
*/
uintptr_t
MM_SweepHeapSectioningSegmented::calculateActualChunkNumbers() const
{
uintptr_t totalChunkCount = 0;
MM_HeapRegionDescriptor *region;
MM_Heap *heap = _extensions->heap;
MM_HeapRegionManager *regionManager = heap->getHeapRegionManager();
GC_HeapRegionIterator regionIterator(regionManager);
while((region = regionIterator.nextRegion()) != NULL) {
if ((region)->isCommitted()) {
/* TODO: this must be rethought for Tarok since it treats all regions identically but some might require different sweep logic */
MM_MemorySubSpace *subspace = region->getSubSpace();
/* if this is a committed region, it requires a non-NULL subspace */
Assert_MM_true(NULL != subspace);
uintptr_t poolCount = subspace->getMemoryPoolCount();
totalChunkCount += MM_Math::roundToCeiling(_extensions->parSweepChunkSize, region->getSize()) / _extensions->parSweepChunkSize;
/* Add extra chunks if more than one memory pool */
totalChunkCount += (poolCount - 1);
}
}
return totalChunkCount;
}
void
MM_MarkMap::initializeMarkMap(MM_EnvironmentBase *env)
{
/* TODO: The multiplier should really be some constant defined globally */
const uintptr_t MODRON_PARALLEL_MULTIPLIER = 32;
uintptr_t heapAlignment = _extensions->heapAlignment;
/* Determine the size of heap that a work unit of mark map clearing corresponds to */
uintptr_t heapClearUnitFactor = env->_currentTask->getThreadCount();
heapClearUnitFactor = ((heapClearUnitFactor == 1) ? 1 : heapClearUnitFactor * MODRON_PARALLEL_MULTIPLIER);
uintptr_t heapClearUnitSize = _extensions->heap->getMemorySize() / heapClearUnitFactor;
heapClearUnitSize = MM_Math::roundToCeiling(heapAlignment, heapClearUnitSize);
/* Walk all object segments to determine what ranges of the mark map should be cleared */
MM_HeapRegionDescriptor *region;
MM_Heap *heap = _extensions->getHeap();
MM_HeapRegionManager *regionManager = heap->getHeapRegionManager();
GC_HeapRegionIterator regionIterator(regionManager);
while(NULL != (region = regionIterator.nextRegion())) {
if (region->isCommitted()) {
/* Walk the segment in chunks the size of the heapClearUnit size, checking if the corresponding mark map
* range should be cleared.
*/
uint8_t* heapClearAddress = (uint8_t*)region->getLowAddress();
uintptr_t heapClearSizeRemaining = region->getSize();
while(0 != heapClearSizeRemaining) {
/* Calculate the size of heap that is to be processed */
uintptr_t heapCurrentClearSize = (heapClearUnitSize > heapClearSizeRemaining) ? heapClearSizeRemaining : heapClearUnitSize;
Assert_MM_true(heapCurrentClearSize > 0);
/* Check if the thread should clear the corresponding mark map range for the current heap range */
if(J9MODRON_HANDLE_NEXT_WORK_UNIT(env)) {
/* Convert the heap address/size to its corresponding mark map address/size */
/* NOTE: We calculate the low and high heap offsets, and build the mark map index and size values
* from these to avoid rounding errors (if we use the size, the conversion routine could get a different
* rounding result then the actual end address)
*/
uintptr_t heapClearOffset = ((uintptr_t)heapClearAddress) - _heapMapBaseDelta;
uintptr_t heapMapClearIndex = convertHeapIndexToHeapMapIndex(env, heapClearOffset, sizeof(uintptr_t));
uintptr_t heapMapClearSize =
convertHeapIndexToHeapMapIndex(env, heapClearOffset + heapCurrentClearSize, sizeof(uintptr_t))
- heapMapClearIndex;
/* And clear the mark map */
OMRZeroMemory((void *) (((uintptr_t)_heapMapBits) + heapMapClearIndex), heapMapClearSize);
}
/* Move to the next address range in the segment */
heapClearAddress += heapCurrentClearSize;
heapClearSizeRemaining -= heapCurrentClearSize;
}
}
}
}
MM_HeapRegionDescriptor *
MM_HeapRegionManagerTarok::internalAcquireSingleTableRegion(MM_EnvironmentBase *env, MM_MemorySubSpace *subSpace, uintptr_t freeListIndex)
{
Assert_MM_true(NULL != _freeRegionTable[freeListIndex]);
/*since we only need one region, always return the first free region */
MM_HeapRegionDescriptor *toReturn = _freeRegionTable[freeListIndex];
_freeRegionTable[freeListIndex] = toReturn->_nextInSet;
toReturn->_nextInSet = NULL;
toReturn->_isAllocated = true;
toReturn->associateWithSubSpace(subSpace);
_totalHeapSize += toReturn->getSize();
return toReturn;
}