/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * 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

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc/g1/g1EvacStats.hpp"

#include "gc/shared/gcId.hpp"

#include "trace/tracing.hpp"

void G1EvacStats::adjust_desired_plab_sz() {

  if (PrintPLAB) {

    gclog_or_tty->print(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "

                        "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "

                        "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "

                        "regions filled = %u direct_allocated = " SIZE_FORMAT " "

                        "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") ",

                        _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,

                        _regions_filled, _direct_allocated, _failure_used, _failure_waste);

  }

  if (ResizePLAB) {

    assert(is_object_aligned(max_size()) && min_size() <= max_size(),

           "PLAB clipping computation may be incorrect");

    if (_allocated == 0) {

      assert((_unused == 0),

             err_msg("Inconsistency in PLAB stats: "

                     "_allocated: "SIZE_FORMAT", "

                     "_wasted: "SIZE_FORMAT", "

                     "_region_end_waste: "SIZE_FORMAT", "

                     "_unused: "SIZE_FORMAT", "

                     "_used  : "SIZE_FORMAT,

                     _allocated, _wasted, _region_end_waste, _unused, used()));

      _allocated = 1;

    }

    // We account region end waste fully to PLAB allocation. This is not completely fair,

    // but is a conservative assumption because PLABs may be sized flexibly while we

    // cannot adjust direct allocations.

    // In some cases, wasted_frac may become > 1 but that just reflects the problem

    // with region_end_waste.

    double wasted_frac    = (double)(_unused + _wasted + _region_end_waste) / (double)_allocated;

    size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);

    if (target_refills == 0) {

      target_refills = 1;

    }

    size_t cur_plab_sz = used() / target_refills;

    // Take historical weighted average

    _filter.sample(cur_plab_sz);

    // Clip from above and below, and align to object boundary

    size_t plab_sz;

    plab_sz = MAX2(min_size(), (size_t)_filter.average());

    plab_sz = MIN2(max_size(), plab_sz);

    plab_sz = align_object_size(plab_sz);

    // Latch the result

    _desired_net_plab_sz = plab_sz;

    if (PrintPLAB) {

      gclog_or_tty->print_cr(" (plab_sz = " SIZE_FORMAT " desired_plab_sz = " SIZE_FORMAT ") ", cur_plab_sz, plab_sz);

    }

  }

  // Clear accumulators for next round.

  reset();

}