src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp

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

author
tschatzl
date
Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257
e7d0505c8a30
parent 7052
8d5f66b42c53
child 7509
ae52ee069062
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

     1 /*
     2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    25 #include "precompiled.hpp"
    26 #include "gc_implementation/g1/g1PageBasedVirtualSpace.hpp"
    27 #include "oops/markOop.hpp"
    28 #include "oops/oop.inline.hpp"
    29 #include "services/memTracker.hpp"
    30 #ifdef TARGET_OS_FAMILY_linux
    31 # include "os_linux.inline.hpp"
    32 #endif
    33 #ifdef TARGET_OS_FAMILY_solaris
    34 # include "os_solaris.inline.hpp"
    35 #endif
    36 #ifdef TARGET_OS_FAMILY_windows
    37 # include "os_windows.inline.hpp"
    38 #endif
    39 #ifdef TARGET_OS_FAMILY_aix
    40 # include "os_aix.inline.hpp"
    41 #endif
    42 #ifdef TARGET_OS_FAMILY_bsd
    43 # include "os_bsd.inline.hpp"
    44 #endif
    45 #include "utilities/bitMap.inline.hpp"
    47 G1PageBasedVirtualSpace::G1PageBasedVirtualSpace() : _low_boundary(NULL),
    48   _high_boundary(NULL), _committed(), _page_size(0), _special(false), _executable(false) {
    49 }
    51 bool G1PageBasedVirtualSpace::initialize_with_granularity(ReservedSpace rs, size_t page_size) {
    52   if (!rs.is_reserved()) {
    53     return false;  // Allocation failed.
    54   }
    55   assert(_low_boundary == NULL, "VirtualSpace already initialized");
    56   assert(page_size > 0, "Granularity must be non-zero.");
    58   _low_boundary  = rs.base();
    59   _high_boundary = _low_boundary + rs.size();
    61   _special = rs.special();
    62   _executable = rs.executable();
    64   _page_size = page_size;
    66   assert(_committed.size() == 0, "virtual space initialized more than once");
    67   uintx size_in_bits = rs.size() / page_size;
    68   _committed.resize(size_in_bits, /* in_resource_area */ false);
    70   return true;
    71 }
    74 G1PageBasedVirtualSpace::~G1PageBasedVirtualSpace() {
    75   release();
    76 }
    78 void G1PageBasedVirtualSpace::release() {
    79   // This does not release memory it never reserved.
    80   // Caller must release via rs.release();
    81   _low_boundary           = NULL;
    82   _high_boundary          = NULL;
    83   _special                = false;
    84   _executable             = false;
    85   _page_size              = 0;
    86   _committed.resize(0, false);
    87 }
    89 size_t G1PageBasedVirtualSpace::committed_size() const {
    90   return _committed.count_one_bits() * _page_size;
    91 }
    93 size_t G1PageBasedVirtualSpace::reserved_size() const {
    94   return pointer_delta(_high_boundary, _low_boundary, sizeof(char));
    95 }
    97 size_t G1PageBasedVirtualSpace::uncommitted_size()  const {
    98   return reserved_size() - committed_size();
    99 }
   101 uintptr_t G1PageBasedVirtualSpace::addr_to_page_index(char* addr) const {
   102   return (addr - _low_boundary) / _page_size;
   103 }
   105 bool G1PageBasedVirtualSpace::is_area_committed(uintptr_t start, size_t size_in_pages) const {
   106   uintptr_t end = start + size_in_pages;
   107   return _committed.get_next_zero_offset(start, end) >= end;
   108 }
   110 bool G1PageBasedVirtualSpace::is_area_uncommitted(uintptr_t start, size_t size_in_pages) const {
   111   uintptr_t end = start + size_in_pages;
   112   return _committed.get_next_one_offset(start, end) >= end;
   113 }
   115 char* G1PageBasedVirtualSpace::page_start(uintptr_t index) {
   116   return _low_boundary + index * _page_size;
   117 }
   119 size_t G1PageBasedVirtualSpace::byte_size_for_pages(size_t num) {
   120   return num * _page_size;
   121 }
   123 MemRegion G1PageBasedVirtualSpace::commit(uintptr_t start, size_t size_in_pages) {
   124   // We need to make sure to commit all pages covered by the given area.
   125   guarantee(is_area_uncommitted(start, size_in_pages), "Specified area is not uncommitted");
   127   if (!_special) {
   128     os::commit_memory_or_exit(page_start(start), byte_size_for_pages(size_in_pages), _executable,
   129                               err_msg("Failed to commit pages from "SIZE_FORMAT" of length "SIZE_FORMAT, start, size_in_pages));
   130   }
   131   _committed.set_range(start, start + size_in_pages);
   133   MemRegion result((HeapWord*)page_start(start), byte_size_for_pages(size_in_pages) / HeapWordSize);
   134   return result;
   135 }
   137 MemRegion G1PageBasedVirtualSpace::uncommit(uintptr_t start, size_t size_in_pages) {
   138   guarantee(is_area_committed(start, size_in_pages), "checking");
   140   if (!_special) {
   141     os::uncommit_memory(page_start(start), byte_size_for_pages(size_in_pages));
   142   }
   144   _committed.clear_range(start, start + size_in_pages);
   146   MemRegion result((HeapWord*)page_start(start), byte_size_for_pages(size_in_pages) / HeapWordSize);
   147   return result;
   148 }
   150 bool G1PageBasedVirtualSpace::contains(const void* p) const {
   151   return _low_boundary <= (const char*) p && (const char*) p < _high_boundary;
   152 }
   154 #ifndef PRODUCT
   155 void G1PageBasedVirtualSpace::print_on(outputStream* out) {
   156   out->print   ("Virtual space:");
   157   if (special()) out->print(" (pinned in memory)");
   158   out->cr();
   159   out->print_cr(" - committed: " SIZE_FORMAT, committed_size());
   160   out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());
   161   out->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(_low_boundary), p2i(_high_boundary));
   162 }
   164 void G1PageBasedVirtualSpace::print() {
   165   print_on(tty);
   166 }
   167 #endif

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