ysr@777: /*
ysr@777:  * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
ysr@777:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
ysr@777:  * CA 95054 USA or visit www.sun.com if you need additional information or
ysr@777:  * have any questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
ysr@777: #include "incls/_precompiled.incl"
ysr@777: #include "incls/_concurrentZFThread.cpp.incl"
ysr@777: 
ysr@777: // ======= Concurrent Zero-Fill Thread ========
ysr@777: 
ysr@777: // The CM thread is created when the G1 garbage collector is used
ysr@777: 
ysr@777: int ConcurrentZFThread::_region_allocs = 0;
ysr@777: int ConcurrentZFThread::_sync_zfs = 0;
ysr@777: int ConcurrentZFThread::_zf_waits = 0;
ysr@777: int ConcurrentZFThread::_regions_filled = 0;
ysr@777: 
ysr@777: ConcurrentZFThread::ConcurrentZFThread() :
ysr@777:   ConcurrentGCThread(),
ysr@777:   _co_tracker(G1ZFGroup)
ysr@777: {
ysr@777:   create_and_start();
ysr@777: }
ysr@777: 
ysr@777: void ConcurrentZFThread::wait_for_ZF_completed(HeapRegion* hr) {
ysr@777:   assert(ZF_mon->owned_by_self(), "Precondition.");
ysr@777:   note_zf_wait();
ysr@777:   while (hr->zero_fill_state() == HeapRegion::ZeroFilling) {
ysr@777:     ZF_mon->wait(Mutex::_no_safepoint_check_flag);
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: void ConcurrentZFThread::processHeapRegion(HeapRegion* hr) {
ysr@777:   assert(!Universe::heap()->is_gc_active(),
ysr@777:          "This should not happen during GC.");
ysr@777:   assert(hr != NULL, "Precondition");
ysr@777:   // These are unlocked reads, but if this test is successful, then no
ysr@777:   // other thread will attempt this zero filling.  Only a GC thread can
ysr@777:   // modify the ZF state of a region whose state is zero-filling, and this
ysr@777:   // should only happen while the ZF thread is locking out GC.
ysr@777:   if (hr->zero_fill_state() == HeapRegion::ZeroFilling
ysr@777:       && hr->zero_filler() == Thread::current()) {
ysr@777:     assert(hr->top() == hr->bottom(), "better be empty!");
ysr@777:     assert(!hr->isHumongous(), "Only free regions on unclean list.");
ysr@777:     Copy::fill_to_words(hr->bottom(), hr->capacity()/HeapWordSize);
ysr@777:     note_region_filled();
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: void ConcurrentZFThread::run() {
ysr@777:   initialize_in_thread();
ysr@777:   Thread* thr_self = Thread::current();
ysr@777:   _vtime_start = os::elapsedVTime();
ysr@777:   wait_for_universe_init();
ysr@777:   _co_tracker.enable();
ysr@777:   _co_tracker.start();
ysr@777: 
ysr@777:   G1CollectedHeap* g1 = G1CollectedHeap::heap();
ysr@777:   _sts.join();
ysr@777:   while (!_should_terminate) {
ysr@777:     _sts.leave();
ysr@777: 
ysr@777:     {
ysr@777:       MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
ysr@777: 
ysr@777:       // This local variable will hold a region being zero-filled.  This
ysr@777:       // region will neither be on the unclean or zero-filled lists, and
ysr@777:       // will not be available for allocation; thus, we might have an
ysr@777:       // allocation fail, causing a full GC, because of this, but this is a
ysr@777:       // price we will pay.  (In future, we might want to make the fact
ysr@777:       // that there's a region being zero-filled apparent to the G1 heap,
ysr@777:       // which could then wait for it in this extreme case...)
ysr@777:       HeapRegion* to_fill;
ysr@777: 
ysr@777:       while (!g1->should_zf()
ysr@777:              || (to_fill = g1->pop_unclean_region_list_locked()) == NULL)
ysr@777:         ZF_mon->wait(Mutex::_no_safepoint_check_flag);
ysr@777:       while (to_fill->zero_fill_state() == HeapRegion::ZeroFilling)
ysr@777:         ZF_mon->wait(Mutex::_no_safepoint_check_flag);
ysr@777: 
ysr@777:       // So now to_fill is non-NULL and is not ZeroFilling.  It might be
ysr@777:       // Allocated or ZeroFilled.  (The latter could happen if this thread
ysr@777:       // starts the zero-filling of a region, but a GC intervenes and
ysr@777:       // pushes new regions needing on the front of the filling on the
ysr@777:       // front of the list.)
ysr@777: 
ysr@777:       switch (to_fill->zero_fill_state()) {
ysr@777:       case HeapRegion::Allocated:
ysr@777:         to_fill = NULL;
ysr@777:         break;
ysr@777: 
ysr@777:       case HeapRegion::NotZeroFilled:
ysr@777:         to_fill->set_zero_fill_in_progress(thr_self);
ysr@777: 
ysr@777:         ZF_mon->unlock();
ysr@777:         _sts.join();
ysr@777:         processHeapRegion(to_fill);
ysr@777:         _sts.leave();
ysr@777:         ZF_mon->lock_without_safepoint_check();
ysr@777: 
ysr@777:         if (to_fill->zero_fill_state() == HeapRegion::ZeroFilling
ysr@777:             && to_fill->zero_filler() == thr_self) {
ysr@777:           to_fill->set_zero_fill_complete();
ysr@777:           (void)g1->put_free_region_on_list_locked(to_fill);
ysr@777:         }
ysr@777:         break;
ysr@777: 
ysr@777:       case HeapRegion::ZeroFilled:
ysr@777:         (void)g1->put_free_region_on_list_locked(to_fill);
ysr@777:         break;
ysr@777: 
ysr@777:       case HeapRegion::ZeroFilling:
ysr@777:         ShouldNotReachHere();
ysr@777:         break;
ysr@777:       }
ysr@777:     }
ysr@777:     _vtime_accum = (os::elapsedVTime() - _vtime_start);
ysr@777:     _sts.join();
ysr@777: 
ysr@777:     _co_tracker.update();
ysr@777:   }
ysr@777:   _co_tracker.update(false);
ysr@777:   _sts.leave();
ysr@777: 
ysr@777:   assert(_should_terminate, "just checking");
ysr@777:   terminate();
ysr@777: }
ysr@777: 
ysr@777: bool ConcurrentZFThread::offer_yield() {
ysr@777:   if (_sts.should_yield()) {
ysr@777:     _sts.yield("Concurrent ZF");
ysr@777:     return true;
ysr@777:   } else {
ysr@777:     return false;
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: void ConcurrentZFThread::stop() {
ysr@777:   // it is ok to take late safepoints here, if needed
ysr@777:   MutexLockerEx mu(Terminator_lock);
ysr@777:   _should_terminate = true;
ysr@777:   while (!_has_terminated) {
ysr@777:     Terminator_lock->wait();
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: void ConcurrentZFThread::print() {
ysr@777:   gclog_or_tty->print("\"Concurrent ZF Thread\" ");
ysr@777:   Thread::print();
ysr@777:   gclog_or_tty->cr();
ysr@777: }
ysr@777: 
ysr@777: 
ysr@777: double ConcurrentZFThread::_vtime_accum;
ysr@777: 
ysr@777: void ConcurrentZFThread::print_summary_info() {
ysr@777:   gclog_or_tty->print("\nConcurrent Zero-Filling:\n");
ysr@777:   gclog_or_tty->print("  Filled %d regions, used %5.2fs.\n",
ysr@777:                       _regions_filled,
ysr@777:                       vtime_accum());
ysr@777:   gclog_or_tty->print("  Of %d region allocs, %d (%5.2f%%) required sync ZF,\n",
ysr@777:                       _region_allocs, _sync_zfs,
ysr@777:                       (_region_allocs > 0 ?
ysr@777:                        (float)_sync_zfs/(float)_region_allocs*100.0 :
ysr@777:                        0.0));
ysr@777:   gclog_or_tty->print("     and %d (%5.2f%%) required a ZF wait.\n",
ysr@777:                       _zf_waits,
ysr@777:                       (_region_allocs > 0 ?
ysr@777:                        (float)_zf_waits/(float)_region_allocs*100.0 :
ysr@777:                        0.0));
ysr@777: 
ysr@777: }