src/hotspot/share/gc/shared/threadLocalAllocBuffer.inline.hpp

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#ifndef SHARE_GC_SHARED_THREADLOCALALLOCBUFFER_INLINE_HPP
#define SHARE_GC_SHARED_THREADLOCALALLOCBUFFER_INLINE_HPP

#include "gc/shared/threadLocalAllocBuffer.hpp"

#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/tlab_globals.hpp"
#include "logging/log.hpp"
#include "memory/universe.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/osThread.hpp"
#include "utilities/copy.hpp"

inline HeapWord* ThreadLocalAllocBuffer::allocate(size_t size) {
  invariants();
  HeapWord* obj = top();
  if (pointer_delta(end(), obj) >= size) {
    // Successful thread-local allocation.

    // This addition is safe because we know that top is
    // at least size below end, so the add can't wrap.
    set_top(obj + size);

    invariants();
    return obj;
  }
  return nullptr;
}

inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) {
  // Compute the size for the new TLAB.
  // The "last" tlab may be smaller to reduce fragmentation.
  // unsafe_max_tlab_alloc is just a hint.
  const size_t available_size = Universe::heap()->unsafe_max_tlab_alloc(thread()) / HeapWordSize;
  size_t new_tlab_size = MIN3(available_size, desired_size() + align_object_size(obj_size), max_size());

  // Make sure there's enough room for object and filler int[].
  if (new_tlab_size < compute_min_size(obj_size)) {
    // If there isn't enough room for the allocation, return failure.
    log_trace(gc, tlab)("ThreadLocalAllocBuffer::compute_size(%zu) returns failure",
                        obj_size);
    return 0;
  }
  log_trace(gc, tlab)("ThreadLocalAllocBuffer::compute_size(%zu) returns %zu",
                      obj_size, new_tlab_size);
  return new_tlab_size;
}

inline size_t ThreadLocalAllocBuffer::compute_min_size(size_t obj_size) {
  const size_t aligned_obj_size = align_object_size(obj_size);
  const size_t size_with_reserve = aligned_obj_size + alignment_reserve();
  return MAX2(size_with_reserve, heap_word_size(MinTLABSize));
}

void ThreadLocalAllocBuffer::record_slow_allocation(size_t obj_size) {
  // Raise size required to bypass TLAB next time. Why? Else there's
  // a risk that a thread that repeatedly allocates objects of one
  // size will get stuck on this slow path.

  set_refill_waste_limit(refill_waste_limit() + refill_waste_limit_increment());

  _slow_allocations++;

  log_develop_trace(gc, tlab)("TLAB: %s thread: " PTR_FORMAT " [id: %2d]"
                              " obj: %zu"
                              " free: %zu"
                              " waste: %zu",
                              "slow", p2i(thread()), thread()->osthread()->thread_id(),
                              obj_size, free(), refill_waste_limit());
}

#endif // SHARE_GC_SHARED_THREADLOCALALLOCBUFFER_INLINE_HPP