jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/vm_operations

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp@5130fa1b24f1 (annotated)

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp

Wed, 15 Jun 2011 10:18:04 -0700

author: johnc
date: Wed, 15 Jun 2011 10:18:04 -0700
changeset 2970: 5130fa1b24f1
parent 2708: 1d1603768966
child 3114: 20213c8a3c40
permissions: -rw-r--r--

7045751: G1: +ExplicitGCInvokesConcurrent causes excessive single region evacuation pauses
Summary: When ExplicitGCInvokesConcurrent is enabled, do not perform an evacuation pause if a marking cycle is already in progress and block the requesting thread until the marking cycle completes.
Reviewed-by: tonyp, ysr

 /*
  * Copyright (c) 2001, 2011, 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
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 #include "precompiled.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
 #include "gc_implementation/shared/isGCActiveMark.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
 #include "runtime/interfaceSupport.hpp"
 VM_G1CollectForAllocation::VM_G1CollectForAllocation(
                                                   unsigned int gc_count_before,
                                                   size_t word_size)
   : VM_G1OperationWithAllocRequest(gc_count_before, word_size) {
   guarantee(word_size > 0, "an allocation should always be requested");
 }
 void VM_G1CollectForAllocation::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
   assert(_result == NULL || _pause_succeeded,
          "if we get back a result, the pause should have succeeded");
 }
 void VM_G1CollectFull::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   GCCauseSetter x(g1h, _gc_cause);
   g1h->do_full_collection(false /* clear_all_soft_refs */);
 }
 VM_G1IncCollectionPause::VM_G1IncCollectionPause(
                                       unsigned int   gc_count_before,
                                       size_t         word_size,
                                       bool           should_initiate_conc_mark,
                                       double         target_pause_time_ms,
                                       GCCause::Cause gc_cause)
   : VM_G1OperationWithAllocRequest(gc_count_before, word_size),
     _should_initiate_conc_mark(should_initiate_conc_mark),
     _target_pause_time_ms(target_pause_time_ms),
     _full_collections_completed_before(0) {
   guarantee(target_pause_time_ms > 0.0,
             err_msg("target_pause_time_ms = %1.6lf should be positive",
                     target_pause_time_ms));
   guarantee(word_size == 0 || gc_cause == GCCause::_g1_inc_collection_pause,
             "we can only request an allocation if the GC cause is for "
             "an incremental GC pause");
   _gc_cause = gc_cause;
 }
 void VM_G1IncCollectionPause::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   assert(!_should_initiate_conc_mark ||
   ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
    (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
          "only a GC locker or a System.gc() induced GC should start a cycle");
   if (_word_size > 0) {
     // An allocation has been requested. So, try to do that first.
     _result = g1h->attempt_allocation_at_safepoint(_word_size,
                                      false /* expect_null_cur_alloc_region */);
     if (_result != NULL) {
       // If we can successfully allocate before we actually do the
       // pause then we will consider this pause successful.
       _pause_succeeded = true;
       return;
     }
   }
   GCCauseSetter x(g1h, _gc_cause);
   if (_should_initiate_conc_mark) {
     // It's safer to read full_collections_completed() here, given
     // that noone else will be updating it concurrently. Since we'll
     // only need it if we're initiating a marking cycle, no point in
     // setting it earlier.
     _full_collections_completed_before = g1h->full_collections_completed();
     // At this point we are supposed to start a concurrent cycle. We
     // will do so if one is not already in progress.
     bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle();
     // The above routine returns true if we were able to force the
     // next GC pause to be an initial mark; it returns false if a
     // marking cycle is already in progress.
     //
     // If a marking cycle is already in progress just return and skip
     // the pause - the requesting thread should block in doit_epilogue
     // until the marking cycle is complete.
     if (!res) {
       assert(_word_size == 0, "ExplicitGCInvokesConcurrent shouldn't be allocating");
       return;
     }
   }
   _pause_succeeded =
     g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
   if (_pause_succeeded && _word_size > 0) {
     // An allocation had been requested.
     _result = g1h->attempt_allocation_at_safepoint(_word_size,
                                       true /* expect_null_cur_alloc_region */);
   } else {
     assert(_result == NULL, "invariant");
   }
 }
 void VM_G1IncCollectionPause::doit_epilogue() {
   VM_GC_Operation::doit_epilogue();
   // If the pause was initiated by a System.gc() and
   // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
   // that just started (or maybe one that was already in progress) to
   // finish.
   if (_gc_cause == GCCause::_java_lang_system_gc &&
       _should_initiate_conc_mark) {
     assert(ExplicitGCInvokesConcurrent,
            "the only way to be here is if ExplicitGCInvokesConcurrent is set");
     G1CollectedHeap* g1h = G1CollectedHeap::heap();
     // In the doit() method we saved g1h->full_collections_completed()
     // in the _full_collections_completed_before field. We have to
     // wait until we observe that g1h->full_collections_completed()
     // has increased by at least one. This can happen if a) we started
     // a cycle and it completes, b) a cycle already in progress
     // completes, or c) a Full GC happens.
     // If the condition has already been reached, there's no point in
     // actually taking the lock and doing the wait.
     if (g1h->full_collections_completed() <=
                                           _full_collections_completed_before) {
       // The following is largely copied from CMS
       Thread* thr = Thread::current();
       assert(thr->is_Java_thread(), "invariant");
       JavaThread* jt = (JavaThread*)thr;
       ThreadToNativeFromVM native(jt);
       MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
       while (g1h->full_collections_completed() <=
                                           _full_collections_completed_before) {
         FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
       }
     }
   }
 }
 void VM_CGC_Operation::doit() {
   gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
   TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
   TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);
   SharedHeap* sh = SharedHeap::heap();
   // This could go away if CollectedHeap gave access to _gc_is_active...
   if (sh != NULL) {
     IsGCActiveMark x;
     _cl->do_void();
   } else {
     _cl->do_void();
   }
 }
 bool VM_CGC_Operation::doit_prologue() {
   Heap_lock->lock();
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
   return true;
 }
 void VM_CGC_Operation::doit_epilogue() {
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
   Heap_lock->unlock();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp@5130fa1b24f1 (annotated)

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp