ageTable.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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 * 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.
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#include "precompiled.hpp"
#include "jvm.h"
#include "gc/shared/ageTable.inline.hpp"
#include "gc/shared/ageTableTracer.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/gc_globals.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/perfData.hpp"
#include "logging/log.hpp"
#include "oops/oop.inline.hpp"
#include "utilities/copy.hpp"

/* Copyright (c) 1992, 2021, Oracle and/or its affiliates, and Stanford University.
   See the LICENSE file for license information. */

AgeTable::AgeTable(bool global) {

  clear();

  if (UsePerfData && global) {

    ResourceMark rm;
    EXCEPTION_MARK;

    const char* agetable_ns = "generation.0.agetable";
    const char* bytes_ns = PerfDataManager::name_space(agetable_ns, "bytes");

    for(int age = 0; age < table_size; age ++) {
      char age_name[10];
      jio_snprintf(age_name, sizeof(age_name), "%2.2d", age);
      const char* cname = PerfDataManager::counter_name(bytes_ns, age_name);
      _perf_sizes[age] = PerfDataManager::create_variable(SUN_GC, cname,
                                                          PerfData::U_Bytes,
                                                          CHECK);
    }

    const char* cname = PerfDataManager::counter_name(agetable_ns, "size");
    PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None,
                                     table_size, CHECK);
  }
}

void AgeTable::clear() {
  for (size_t* p = sizes; p < sizes + table_size; ++p) {
    *p = 0;
  }
}

void AgeTable::merge(AgeTable* subTable) {
  for (int i = 0; i < table_size; i++) {
    sizes[i]+= subTable->sizes[i];
  }
}

uint AgeTable::compute_tenuring_threshold(size_t desired_survivor_size) {
  uint result;

  if (AlwaysTenure || NeverTenure) {
    assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
           "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is " UINTX_FORMAT, MaxTenuringThreshold);
    result = MaxTenuringThreshold;
  } else {
    size_t total = 0;
    uint age = 1;
    assert(sizes[0] == 0, "no objects with age zero should be recorded");
    while (age < table_size) {
      total += sizes[age];
      // check if including objects of age 'age' made us pass the desired
      // size, if so 'age' is the new threshold
      if (total > desired_survivor_size) break;
      age++;
    }
    result = age < MaxTenuringThreshold ? age : MaxTenuringThreshold;
  }


  log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold " UINTX_FORMAT " (max threshold " UINTX_FORMAT ")",
                     desired_survivor_size * oopSize, (uintx) result, MaxTenuringThreshold);

  return result;
}

void AgeTable::print_age_table(uint tenuring_threshold) {
  if (log_is_enabled(Trace, gc, age) || UsePerfData || AgeTableTracer::is_tenuring_distribution_event_enabled()) {
    log_trace(gc, age)("Age table with threshold %u (max threshold " UINTX_FORMAT ")",
                       tenuring_threshold, MaxTenuringThreshold);

    size_t total = 0;
    uint age = 1;
    while (age < table_size) {
      size_t wordSize = sizes[age];
      total += wordSize;
      if (wordSize > 0) {
        log_trace(gc, age)("- age %3u: " SIZE_FORMAT_W(10) " bytes, " SIZE_FORMAT_W(10) " total",
                            age, wordSize * oopSize, total * oopSize);
      }
      AgeTableTracer::send_tenuring_distribution_event(age, wordSize * oopSize);
      if (UsePerfData) {
        _perf_sizes[age]->set_value(wordSize * oopSize);
      }
      age++;
    }
  }
}