jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1BiasedArray.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BiasedArray.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BiasedArray.cpp

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 6680: 78bbf4d43a14
child 6876: 710a3c8b516e
child 9327: f96fcd9e1e1b
permissions: -rw-r--r--

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

 /*
  * Copyright (c) 2013, 2014, 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_implementation/g1/g1BiasedArray.hpp"
 #include "memory/padded.inline.hpp"
 // Allocate a new array, generic version.
 address G1BiasedMappedArrayBase::create_new_base_array(size_t length, size_t elem_size) {
   assert(length > 0, "just checking");
   assert(elem_size > 0, "just checking");
   return PaddedPrimitiveArray<u_char, mtGC>::create_unfreeable(length * elem_size);
 }
 #ifndef PRODUCT
 void G1BiasedMappedArrayBase::verify_index(idx_t index) const {
   guarantee(_base != NULL, "Array not initialized");
   guarantee(index < length(), err_msg("Index out of bounds index: "SIZE_FORMAT" length: "SIZE_FORMAT, index, length()));
 }
 void G1BiasedMappedArrayBase::verify_biased_index(idx_t biased_index) const {
   guarantee(_biased_base != NULL, "Array not initialized");
   guarantee(biased_index >= bias() && biased_index < (bias() + length()),
     err_msg("Biased index out of bounds, index: "SIZE_FORMAT" bias: "SIZE_FORMAT" length: "SIZE_FORMAT, biased_index, bias(), length()));
 }
 void G1BiasedMappedArrayBase::verify_biased_index_inclusive_end(idx_t biased_index) const {
   guarantee(_biased_base != NULL, "Array not initialized");
   guarantee(biased_index >= bias() && biased_index <= (bias() + length()),
     err_msg("Biased index out of inclusive bounds, index: "SIZE_FORMAT" bias: "SIZE_FORMAT" length: "SIZE_FORMAT, biased_index, bias(), length()));
 }
 class TestMappedArray : public G1BiasedMappedArray<int> {
 protected:
   virtual int default_value() const { return 0xBAADBABE; }
 public:
   static void test_biasedarray() {
     const size_t REGION_SIZE_IN_WORDS = 512;
     const size_t NUM_REGIONS = 20;
     HeapWord* fake_heap = (HeapWord*)LP64_ONLY(0xBAAA00000) NOT_LP64(0xBA000000); // Any value that is non-zero
     TestMappedArray array;
     array.initialize(fake_heap, fake_heap + REGION_SIZE_IN_WORDS * NUM_REGIONS,
             REGION_SIZE_IN_WORDS * HeapWordSize);
     // Check address calculation (bounds)
     assert(array.bottom_address_mapped() == fake_heap,
       err_msg("bottom mapped address should be " PTR_FORMAT ", but is " PTR_FORMAT, p2i(fake_heap), p2i(array.bottom_address_mapped())));
     assert(array.end_address_mapped() == (fake_heap + REGION_SIZE_IN_WORDS * NUM_REGIONS), "must be");
     int* bottom = array.address_mapped_to(fake_heap);
     assert((void*)bottom == (void*) array.base(), "must be");
     int* end = array.address_mapped_to(fake_heap + REGION_SIZE_IN_WORDS * NUM_REGIONS);
     assert((void*)end == (void*)(array.base() + array.length()), "must be");
     // The entire array should contain default value elements
     for (int* current = bottom; current < end; current++) {
       assert(*current == array.default_value(), "must be");
     }
     // Test setting values in the table
     HeapWord* region_start_address = fake_heap + REGION_SIZE_IN_WORDS * (NUM_REGIONS / 2);
     HeapWord* region_end_address = fake_heap + (REGION_SIZE_IN_WORDS * (NUM_REGIONS / 2) + REGION_SIZE_IN_WORDS - 1);
     // Set/get by address tests: invert some value; first retrieve one
     int actual_value = array.get_by_index(NUM_REGIONS / 2);
     array.set_by_index(NUM_REGIONS / 2, ~actual_value);
     // Get the same value by address, should correspond to the start of the "region"
     int value = array.get_by_address(region_start_address);
     assert(value == ~actual_value, "must be");
     // Get the same value by address, at one HeapWord before the start
     value = array.get_by_address(region_start_address - 1);
     assert(value == array.default_value(), "must be");
     // Get the same value by address, at the end of the "region"
     value = array.get_by_address(region_end_address);
     assert(value == ~actual_value, "must be");
     // Make sure the next value maps to another index
     value = array.get_by_address(region_end_address + 1);
     assert(value == array.default_value(), "must be");
     // Reset the value in the array
     array.set_by_address(region_start_address + (region_end_address - region_start_address) / 2, actual_value);
     // The entire array should have the default value again
     for (int* current = bottom; current < end; current++) {
       assert(*current == array.default_value(), "must be");
     }
     // Set/get by index tests: invert some value
     idx_t index = NUM_REGIONS / 2;
     actual_value = array.get_by_index(index);
     array.set_by_index(index, ~actual_value);
     value = array.get_by_index(index);
     assert(value == ~actual_value, "must be");
     value = array.get_by_index(index - 1);
     assert(value == array.default_value(), "must be");
     value = array.get_by_index(index + 1);
     assert(value == array.default_value(), "must be");
     array.set_by_index(0, 0);
     value = array.get_by_index(0);
     assert(value == 0, "must be");
     array.set_by_index(array.length() - 1, 0);
     value = array.get_by_index(array.length() - 1);
     assert(value == 0, "must be");
     array.set_by_index(index, 0);
     // The array should have three zeros, and default values otherwise
     size_t num_zeros = 0;
     for (int* current = bottom; current < end; current++) {
       assert(*current == array.default_value() || *current == 0, "must be");
       if (*current == 0) {
         num_zeros++;
       }
     }
     assert(num_zeros == 3, "must be");
   }
 };
 void TestG1BiasedArray_test() {
   TestMappedArray::test_biasedarray();
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1BiasedArray.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BiasedArray.cpp