GC clean up.
Greater use of directories and namespaces.
Fix bugs that cause verify options to fail.
Address numerous other issues:
GC barrier wait occurring holding locks:
GC barrier waits occur when we wait for threads to run the check point function
on themselves. This is happening with the heap bitmap and mutator lock held
meaning that a thread that tries to take either lock exclusively will block
waiting on a thread that is waiting. If this thread is the thread we're waiting
to run the check point then the VM will deadlock.
This deadlock occurred unnoticed as the call to check for wait safety was
removed in: https://googleplex-android-review.googlesource.com/#/c/249423/1.
NewTimingLogger:
Existing timing log states when a split ends but not when it begins. This isn't
good for systrace, in the context of GC it means that races between mutators
and the GC are hard to discover what phase the GC is in, we know what phase it
just finished and derive but that's not ideal.
Support for only 1 discontinuous space:
Code special cases continuous and large object space, rather than assuming we
can have a collection of both.
Sorted atomic stacks:
Used to improve verification performance. Simplify their use and add extra
checks.
Simplify mod-union table abstractions.
Reduce use of std::strings and their associated overhead in hot code.
Make time units of fields explicit.
Reduce confusion that IsAllocSpace is really IsDlMallocSpace.
Make GetTotalMemory (exposed via System) equal to the footprint (as in Dalvik)
rather than the max memory footprint.
Change-Id: Ie87067140fa4499b15edab691fe6565d79599812
diff --git a/src/gc/accounting/card_table.cc b/src/gc/accounting/card_table.cc
new file mode 100644
index 0000000..4f2ae26
--- /dev/null
+++ b/src/gc/accounting/card_table.cc
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "card_table.h"
+
+#include "base/logging.h"
+#include "card_table-inl.h"
+#include "gc/heap.h"
+#include "gc/space/space.h"
+#include "heap_bitmap.h"
+#include "runtime.h"
+#include "utils.h"
+
+namespace art {
+namespace gc {
+namespace accounting {
+
+/*
+ * Maintain a card table from the write barrier. All writes of
+ * non-NULL values to heap addresses should go through an entry in
+ * WriteBarrier, and from there to here.
+ *
+ * The heap is divided into "cards" of GC_CARD_SIZE bytes, as
+ * determined by GC_CARD_SHIFT. The card table contains one byte of
+ * data per card, to be used by the GC. The value of the byte will be
+ * one of GC_CARD_CLEAN or GC_CARD_DIRTY.
+ *
+ * After any store of a non-NULL object pointer into a heap object,
+ * code is obliged to mark the card dirty. The setters in
+ * object.h [such as SetFieldObject] do this for you. The
+ * compiler also contains code to mark cards as dirty.
+ *
+ * The card table's base [the "biased card table"] gets set to a
+ * rather strange value. In order to keep the JIT from having to
+ * fabricate or load GC_DIRTY_CARD to store into the card table,
+ * biased base is within the mmap allocation at a point where its low
+ * byte is equal to GC_DIRTY_CARD. See CardTable::Create for details.
+ */
+
+CardTable* CardTable::Create(const byte* heap_begin, size_t heap_capacity) {
+ /* Set up the card table */
+ size_t capacity = heap_capacity / kCardSize;
+ /* Allocate an extra 256 bytes to allow fixed low-byte of base */
+ UniquePtr<MemMap> mem_map(MemMap::MapAnonymous("card table", NULL,
+ capacity + 256, PROT_READ | PROT_WRITE));
+ CHECK(mem_map.get() != NULL) << "couldn't allocate card table";
+ // All zeros is the correct initial value; all clean. Anonymous mmaps are initialized to zero, we
+ // don't clear the card table to avoid unnecessary pages being allocated
+ COMPILE_ASSERT(kCardClean == 0, card_clean_must_be_0);
+
+ byte* cardtable_begin = mem_map->Begin();
+ CHECK(cardtable_begin != NULL);
+
+ // We allocated up to a bytes worth of extra space to allow biased_begin's byte value to equal
+ // GC_CARD_DIRTY, compute a offset value to make this the case
+ size_t offset = 0;
+ byte* biased_begin = reinterpret_cast<byte*>(reinterpret_cast<uintptr_t>(cardtable_begin) -
+ (reinterpret_cast<uintptr_t>(heap_begin) >> kCardShift));
+ if (((uintptr_t)biased_begin & 0xff) != kCardDirty) {
+ int delta = kCardDirty - (reinterpret_cast<int>(biased_begin) & 0xff);
+ offset = delta + (delta < 0 ? 0x100 : 0);
+ biased_begin += offset;
+ }
+ CHECK_EQ(reinterpret_cast<int>(biased_begin) & 0xff, kCardDirty);
+
+ return new CardTable(mem_map.release(), biased_begin, offset);
+}
+
+CardTable::CardTable(MemMap* mem_map, byte* biased_begin, size_t offset)
+ : mem_map_(mem_map), biased_begin_(biased_begin), offset_(offset) {
+ byte* __attribute__((unused)) begin = mem_map_->Begin() + offset_;
+ byte* __attribute__((unused)) end = mem_map_->End();
+}
+
+void CardTable::ClearSpaceCards(space::ContinuousSpace* space) {
+ // TODO: clear just the range of the table that has been modified
+ byte* card_start = CardFromAddr(space->Begin());
+ byte* card_end = CardFromAddr(space->End()); // Make sure to round up.
+ memset(reinterpret_cast<void*>(card_start), kCardClean, card_end - card_start);
+}
+
+void CardTable::ClearCardTable() {
+ // TODO: clear just the range of the table that has been modified
+ memset(mem_map_->Begin(), kCardClean, mem_map_->Size());
+}
+
+bool CardTable::AddrIsInCardTable(const void* addr) const {
+ return IsValidCard(biased_begin_ + ((uintptr_t)addr >> kCardShift));
+}
+
+void CardTable::CheckAddrIsInCardTable(const byte* addr) const {
+ byte* card_addr = biased_begin_ + ((uintptr_t)addr >> kCardShift);
+ byte* begin = mem_map_->Begin() + offset_;
+ byte* end = mem_map_->End();
+ CHECK(AddrIsInCardTable(addr))
+ << "Card table " << this
+ << " begin: " << reinterpret_cast<void*>(begin)
+ << " end: " << reinterpret_cast<void*>(end)
+ << " card_addr: " << reinterpret_cast<void*>(card_addr)
+ << " heap begin: " << AddrFromCard(begin)
+ << " heap end: " << AddrFromCard(end)
+ << " addr: " << reinterpret_cast<const void*>(addr);
+}
+
+void CardTable::VerifyCardTable() {
+ UNIMPLEMENTED(WARNING) << "Card table verification";
+}
+
+} // namespace accounting
+} // namespace gc
+} // namespace art