Merge google-perftools r109 (the current contents of third_party/tcmalloc/vendor)

third_party/tcmalloc/chromium/src/central_freelist.cc

 // Copyright (c) 2008, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // ---
 // Author: Sanjay Ghemawat <opensource@google.com>
 
 #include "config.h"
 #include "central_freelist.h"
 
-#include "linked_list.h"
-#include "static_vars.h"
+#include "internal_logging.h"  // for ASSERT, MESSAGE
+#include "linked_list.h"       // for SLL_Next, SLL_Push, etc
+#include "page_heap.h"         // for PageHeap
+#include "static_vars.h"       // for Static
 
 namespace tcmalloc {
 
 void CentralFreeList::Init(size_t cl) {
   size_class_ = cl;
   tcmalloc::DLL_Init(&empty_);
   tcmalloc::DLL_Init(&nonempty_);
   counter_ = 0;
 
-  cache_size_ = 1;
+#ifdef TCMALLOC_SMALL_BUT_SLOW
+  // Disable the transfer cache for the small footprint case.
+  cache_size_ = 0;
+#else
+  cache_size_ = 16;
+#endif
   used_slots_ = 0;
   ASSERT(cache_size_ <= kNumTransferEntries);
 }
 
 void CentralFreeList::ReleaseListToSpans(void* start) {
   while (start) {
     void *next = SLL_Next(start);
     ReleaseToSpans(start);
     start = next;
   }
 }
 
-void CentralFreeList::ReleaseToSpans(void* object) {
+// MapObjectToSpan should logically be part of ReleaseToSpans.  But
+// this triggers an optimization bug in gcc 4.5.0.  Moving to a
+// separate function, and making sure that function isn't inlined,
+// seems to fix the problem.  It also should be fixed for gcc 4.5.1.
+static
+#if __GNUC__ == 4 && __GNUC_MINOR__ == 5 && __GNUC_PATCHLEVEL__ == 0
+__attribute__ ((noinline))
+#endif
+Span* MapObjectToSpan(void* object) {
   const PageID p = reinterpret_cast<uintptr_t>(object) >> kPageShift;
   Span* span = Static::pageheap()->GetDescriptor(p);
+  return span;
+}
+
+void CentralFreeList::ReleaseToSpans(void* object) {
+  Span* span = MapObjectToSpan(object);
   ASSERT(span != NULL);
   ASSERT(span->refcount > 0);
 
   // If span is empty, move it to non-empty list
   if (span->objects == NULL) {
     tcmalloc::DLL_Remove(span);
     tcmalloc::DLL_Prepend(&nonempty_, span);
     Event(span, 'N', 0);
   }
 
@@ skipping 49 matching lines @@
 
 bool CentralFreeList::MakeCacheSpace() {
   // Is there room in the cache?
   if (used_slots_ < cache_size_) return true;
   // Check if we can expand this cache?
   if (cache_size_ == kNumTransferEntries) return false;
   // Ok, we'll try to grab an entry from some other size class.
   if (EvictRandomSizeClass(size_class_, false) ||
       EvictRandomSizeClass(size_class_, true)) {
     // Succeeded in evicting, we're going to make our cache larger.
-    cache_size_++;
-    return true;
+    // However, we may have dropped and re-acquired the lock in
+    // EvictRandomSizeClass (via ShrinkCache and the LockInverter), so the
+    // cache_size may have changed.  Therefore, check and verify that it is
+    // still OK to increase the cache_size.
+    if (cache_size_ < kNumTransferEntries) {
+      cache_size_++;
+      return true;
+    }
   }
   return false;
 }
 
 
 namespace {
 class LockInverter {
  private:
   SpinLock *held_, *temp_;
  public:
@@ skipping 160 matching lines @@
   tcmalloc::DLL_Prepend(&nonempty_, span);
   counter_ += num;
 }
 
 int CentralFreeList::tc_length() {
   SpinLockHolder h(&lock_);
   return used_slots_ * Static::sizemap()->num_objects_to_move(size_class_);
 }
 
 }  // namespace tcmalloc