src/hotspot/share/gc/z/zNMT.cpp

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#include "gc/z/zAddress.inline.hpp"
#include "gc/z/zGlobals.hpp"
#include "gc/z/zNMT.hpp"
#include "nmt/memoryFileTracker.hpp"
#include "nmt/memTag.hpp"
#include "nmt/memTracker.hpp"
#include "utilities/nativeCallStack.hpp"

MemoryFileTracker::MemoryFile* ZNMT::_device = nullptr;

void ZNMT::initialize() {
  _device = MemTracker::register_file("ZGC heap backing file");
}

void ZNMT::reserve(zaddress_unsafe start, size_t size) {
  MemTracker::record_virtual_memory_reserve((address)untype(start), size, CALLER_PC, mtJavaHeap);
}

void ZNMT::unreserve(zaddress_unsafe start, size_t size) {
  precond(is_aligned(untype(start), ZGranuleSize));
  precond(is_aligned(size, ZGranuleSize));

  if (MemTracker::enabled()) {
    // We are the owner of the reserved memory, and any failure to unreserve
    // are fatal, so so we don't need to hold a lock while unreserving memory.

    MemTracker::NmtVirtualMemoryLocker nvml;

    // The current NMT implementation does not support unreserving a memory
    // region that was built up from smaller memory reservations. Workaround
    // this problem by splitting the work up into granule-sized chunks, which
    // is the smallest unit we ever reserve.
    for (size_t i = 0; i < size; i += ZGranuleSize) {
      MemTracker::record_virtual_memory_release((address)untype(start + i), ZGranuleSize);
    }
  }
}

void ZNMT::commit(zbacking_offset offset, size_t size) {
  MemTracker::allocate_memory_in(ZNMT::_device, untype(offset), size, CALLER_PC, mtJavaHeap);
}

void ZNMT::uncommit(zbacking_offset offset, size_t size) {
  MemTracker::free_memory_in(ZNMT::_device, untype(offset), size);
}

void ZNMT::map(zaddress_unsafe addr, size_t size, zbacking_offset offset) {
  // NMT doesn't track mappings at the moment.
}

void ZNMT::unmap(zaddress_unsafe addr, size_t size) {
  // NMT doesn't track mappings at the moment.
}