Add notion of released vs empty pages to ROSAlloc.
A notion of released vs empty pages helps get a more accurate view of
how much memory was released during heap trimming. Otherwise we get
that the same pages possibly get madvised multiple times without
getting dirtied.
Also enabled heap trimming of rosalloc spaces even when we care about
jank. This is safe to do since the trimming process only acquires
locks for short periods of time.
Dalvik PSS reduces from ~52M to ~50M after boot on N4.
Bug: 9969166
Change-Id: I4012e0a2554f413d18efe1a0371fe18d1edabaa9
diff --git a/runtime/gc/allocator/rosalloc.h b/runtime/gc/allocator/rosalloc.h
index 13f61ec..fad0dc8 100644
--- a/runtime/gc/allocator/rosalloc.h
+++ b/runtime/gc/allocator/rosalloc.h
@@ -99,27 +99,8 @@
byte* start = reinterpret_cast<byte*>(this);
size_t byte_size = ByteSize(rosalloc);
DCHECK_EQ(byte_size % kPageSize, static_cast<size_t>(0));
- bool release_pages = ShouldReleasePages(rosalloc);
- if (kIsDebugBuild) {
- // Exclude the first page that stores the magic number.
- DCHECK_GE(byte_size, static_cast<size_t>(kPageSize));
- start += kPageSize;
- byte_size -= kPageSize;
- if (byte_size > 0) {
- if (release_pages) {
- if (!kMadviseZeroes) {
- memset(start, 0, byte_size);
- }
- madvise(start, byte_size, MADV_DONTNEED);
- }
- }
- } else {
- if (release_pages) {
- if (!kMadviseZeroes) {
- memset(start, 0, byte_size);
- }
- madvise(start, byte_size, MADV_DONTNEED);
- }
+ if (ShouldReleasePages(rosalloc)) {
+ rosalloc->ReleasePageRange(start, start + byte_size);
}
}
};
@@ -462,14 +443,15 @@
std::string size_bracket_lock_names[kNumOfSizeBrackets];
// The types of page map entries.
enum {
- kPageMapEmpty = 0, // Not allocated.
- kPageMapRun = 1, // The beginning of a run.
- kPageMapRunPart = 2, // The non-beginning part of a run.
- kPageMapLargeObject = 3, // The beginning of a large object.
- kPageMapLargeObjectPart = 4, // The non-beginning part of a large object.
+ kPageMapReleased = 0, // Zero and released back to the OS.
+ kPageMapEmpty, // Zero but probably dirty.
+ kPageMapRun, // The beginning of a run.
+ kPageMapRunPart, // The non-beginning part of a run.
+ kPageMapLargeObject, // The beginning of a large object.
+ kPageMapLargeObjectPart, // The non-beginning part of a large object.
};
// The table that indicates what pages are currently used for.
- byte* page_map_; // No GUARDED_BY(lock_) for kReadPageMapEntryWithoutLockInBulkFree.
+ volatile byte* page_map_; // No GUARDED_BY(lock_) for kReadPageMapEntryWithoutLockInBulkFree.
size_t page_map_size_;
size_t max_page_map_size_;
std::unique_ptr<MemMap> page_map_mem_map_;
@@ -536,6 +518,9 @@
// Revoke the current runs which share an index with the thread local runs.
void RevokeThreadUnsafeCurrentRuns();
+ // Release a range of pages.
+ size_t ReleasePageRange(byte* start, byte* end) EXCLUSIVE_LOCKS_REQUIRED(lock_);
+
public:
RosAlloc(void* base, size_t capacity, size_t max_capacity,
PageReleaseMode page_release_mode,
@@ -588,6 +573,11 @@
static Run* GetDedicatedFullRun() {
return dedicated_full_run_;
}
+ bool IsFreePage(size_t idx) const {
+ DCHECK_LT(idx, capacity_ / kPageSize);
+ byte pm_type = page_map_[idx];
+ return pm_type == kPageMapReleased || pm_type == kPageMapEmpty;
+ }
// Callbacks for InspectAll that will count the number of bytes
// allocated and objects allocated, respectively.