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

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
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#include "gc/z/zTLABUsage.hpp"
#include "logging/log.hpp"
#include "runtime/atomic.hpp"

ZTLABUsage::ZTLABUsage()
  : _used(0),
    _used_history() {}

void ZTLABUsage::increase_used(size_t size) {
  Atomic::add(&_used, size, memory_order_relaxed);
}

void ZTLABUsage::decrease_used(size_t size) {
  precond(size <= _used);

  Atomic::sub(&_used, size, memory_order_relaxed);
}

void ZTLABUsage::reset() {
  const size_t used = Atomic::xchg(&_used, (size_t) 0);

  // Avoid updates when nothing has been allocated since the last YC
  if (used == 0) {
    return;
  }

  // Save the old values for logging
  const size_t old_tlab_used = tlab_used();
  const size_t old_tlab_capacity = tlab_capacity();

  // Update the usage history with the current value
  _used_history.add(used);

  log_debug(gc, tlab)("TLAB usage update: used %zuM -> %zuM, capacity: %zuM -> %zuM",
                      old_tlab_used / M,
                      tlab_used() / M,
                      old_tlab_capacity / M,
                      tlab_capacity() / M);
  }

size_t ZTLABUsage::tlab_used() const {
  return _used_history.last();
}

size_t ZTLABUsage::tlab_capacity() const {
  return _used_history.davg();
}