src/hotspot/share/gc/parallel/asPSOldGen.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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 "precompiled.hpp"
#include "gc/parallel/asPSOldGen.hpp"
#include "gc/parallel/parallelScavengeHeap.hpp"
#include "gc/parallel/psAdaptiveSizePolicy.hpp"
#include "gc/parallel/psMarkSweepDecorator.hpp"
#include "gc/shared/cardTableBarrierSet.hpp"
#include "gc/shared/genArguments.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/java.hpp"
#include "utilities/align.hpp"

// Whereas PSOldGen takes the maximum size of the generation
// (which doesn't change in the case of PSOldGen) as a parameter,
// ASPSOldGen takes the upper limit on the size of
// the generation as a parameter.  In ASPSOldGen the
// maximum size of the generation can change as the boundary
// moves.  The "maximum size of the generation" is still a valid
// concept since the generation can grow and shrink within that
// maximum.  There are lots of useful checks that use that
// maximum.  In PSOldGen the method max_gen_size() returns
// _max_gen_size (as set by the PSOldGen constructor).  This
// is how it always worked.  In ASPSOldGen max_gen_size()
// returned the size of the reserved space for the generation.
// That can change as the boundary moves.  Below the limit of
// the size of the generation is passed to the PSOldGen constructor
// for "_max_gen_size" (have to pass something) but it is not used later.
//
ASPSOldGen::ASPSOldGen(size_t initial_size,
                       size_t min_size,
                       size_t size_limit,
                       const char* gen_name,
                       int level) :
  PSOldGen(initial_size, min_size, size_limit, gen_name, level),
  _gen_size_limit(size_limit)
{}

ASPSOldGen::ASPSOldGen(PSVirtualSpace* vs,
                       size_t initial_size,
                       size_t min_size,
                       size_t size_limit,
                       const char* gen_name,
                       int level) :
  PSOldGen(initial_size, min_size, size_limit, gen_name, level),
  _gen_size_limit(size_limit)
{
  _virtual_space = vs;
}

void ASPSOldGen::initialize_work(const char* perf_data_name, int level) {
  PSOldGen::initialize_work(perf_data_name, level);

  // The old gen can grow to gen_size_limit().  _reserve reflects only
  // the current maximum that can be committed.
  assert(_reserved.byte_size() <= gen_size_limit(), "Consistency check");

  initialize_performance_counters(perf_data_name, level);
}

void ASPSOldGen::reset_after_change() {
  _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
                        (HeapWord*)virtual_space()->high_boundary());
  post_resize();
}


size_t ASPSOldGen::available_for_expansion() {
  assert(virtual_space()->is_aligned(gen_size_limit()), "not aligned");
  assert(gen_size_limit() >= virtual_space()->committed_size(), "bad gen size");

  size_t result =  gen_size_limit() - virtual_space()->committed_size();
  size_t result_aligned = align_down(result, GenAlignment);
  return result_aligned;
}

size_t ASPSOldGen::available_for_contraction() {
  size_t uncommitted_bytes = virtual_space()->uncommitted_size();
  if (uncommitted_bytes != 0) {
    return uncommitted_bytes;
  }

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  PSAdaptiveSizePolicy* policy = heap->size_policy();
  const size_t working_size =
    used_in_bytes() + (size_t) policy->avg_promoted()->padded_average();
  const size_t working_aligned = align_up(working_size, GenAlignment);
  const size_t working_or_min = MAX2(working_aligned, min_gen_size());
  if (working_or_min > reserved().byte_size()) {
    // If the used or minimum gen size (aligned up) is greater
    // than the total reserved size, then the space available
    // for contraction should (after proper alignment) be 0
    return 0;
  }
  const size_t max_contraction =
    reserved().byte_size() - working_or_min;

  // Use the "increment" fraction instead of the "decrement" fraction
  // to allow the other gen to expand more aggressively.  The
  // "decrement" fraction is conservative because its intent is to
  // only reduce the footprint.

  size_t result = policy->promo_increment_aligned_down(max_contraction);
  // Also adjust for inter-generational alignment
  size_t result_aligned = align_down(result, GenAlignment);

  Log(gc, ergo) log;
  if (log.is_trace()) {
    size_t working_promoted = (size_t) policy->avg_promoted()->padded_average();
    size_t promo_increment = policy->promo_increment(max_contraction);
    log.trace("ASPSOldGen::available_for_contraction: " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, result_aligned/K, result_aligned);
    log.trace(" reserved().byte_size() " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, reserved().byte_size()/K, reserved().byte_size());
    log.trace(" padded promoted " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, working_promoted/K, working_promoted);
    log.trace(" used " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, used_in_bytes()/K, used_in_bytes());
    log.trace(" min_gen_size() " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, min_gen_size()/K, min_gen_size());
    log.trace(" max_contraction " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, max_contraction/K, max_contraction);
    log.trace("    without alignment " SIZE_FORMAT " K / " SIZE_FORMAT_HEX, promo_increment/K, promo_increment);
    log.trace(" alignment " SIZE_FORMAT_HEX, GenAlignment);
  }

  assert(result_aligned <= max_contraction, "arithmetic is wrong");
  return result_aligned;
}