Changeset 204387 in webkit

Timestamp:

Aug 11, 2016, 2:18:14 PM (8 years ago)

Author:

mark.lam@apple.com

Message:

Disallow synchronous sweeping for eden GCs.
​https://bugs.webkit.org/show_bug.cgi?id=160716

Reviewed by Geoffrey Garen.

JSTests:

• stress/eden-gc-with-retired-blocks.js: Added.
• This test is just in case we add back support for eden GCs with synchronous sweeping in the future.

Source/JavaScriptCore:

• heap/Heap.cpp:

(JSC::Heap::collectAllGarbage):
(JSC::Heap::collectAndSweep): Deleted.

• heap/Heap.h:

(JSC::Heap::collectAllGarbage): Deleted.

• No need for a separate collectAndSweep() anymore since we only call it for FullCollections.
• Since we've already swept all the blocks, I cleared m_blockSnapshot so that the IncrementalSweeper can bail earlier when it runs later.

• heap/MarkedBlock.cpp:

(JSC::MarkedBlock::sweepHelper):

• Removed the unreachable return statement.

• heap/MarkedBlock.h:
• Document what "Retired" means.

• tools/JSDollarVMPrototype.cpp:

(JSC::JSDollarVMPrototype::edenGC):

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/stress/eden-gc-with-retired-blocks.js (added)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/heap/Heap.cpp (modified) (1 diff)
• Source/JavaScriptCore/heap/Heap.h (modified) (1 diff)
• Source/JavaScriptCore/heap/MarkedBlock.cpp (modified) (1 diff)
• Source/JavaScriptCore/heap/MarkedBlock.h (modified) (2 diffs)
• Source/JavaScriptCore/tools/JSDollarVMPrototype.cpp (modified) (1 diff)

trunk/JSTests/ChangeLog

@@ +1 @@
+2016-08-10  Mark Lam  <mark.lam@apple.com>
+
+        Disallow synchronous sweeping for eden GCs.
+        https://bugs.webkit.org/show_bug.cgi?id=160716
+
+        Reviewed by Geoffrey Garen.
+
+        * stress/eden-gc-with-retired-blocks.js: Added.
+        - This test is just in case we add back support for eden GCs with synchronous
+          sweeping in the future.
+
 2016-08-10  Michael Saboff  <msaboff@apple.com>
 

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-08-10  Mark Lam  <mark.lam@apple.com>
+
+        Disallow synchronous sweeping for eden GCs.
+        https://bugs.webkit.org/show_bug.cgi?id=160716
+
+        Reviewed by Geoffrey Garen.
+
+        * heap/Heap.cpp:
+        (JSC::Heap::collectAllGarbage):
+        (JSC::Heap::collectAndSweep): Deleted.
+        * heap/Heap.h:
+        (JSC::Heap::collectAllGarbage): Deleted.
+        - No need for a separate collectAndSweep() anymore since we only call it for
+          FullCollections.
+        - Since we've already swept all the blocks, I cleared m_blockSnapshot so that the
+          IncrementalSweeper can bail earlier when it runs later.
+
+        * heap/MarkedBlock.cpp:
+        (JSC::MarkedBlock::sweepHelper):
+        - Removed the unreachable return statement.
+
+        * heap/MarkedBlock.h:
+        - Document what "Retired" means.
+
+        * tools/JSDollarVMPrototype.cpp:
+        (JSC::JSDollarVMPrototype::edenGC):
+
 2016-08-11  Per Arne Vollan  <pvollan@apple.com>
 

trunk/Source/JavaScriptCore/heap/Heap.cpp

@@ -1072 +1072 @@
 }
 
-void Heap::collectAndSweep(HeapOperation collectionType)
+void Heap::collectAllGarbage()
 {
     if (!m_isSafeToCollect)
         return;
 
-    collect(collectionType);
+    collect(FullCollection);
 
     DeferGCForAWhile deferGC(*this);
     m_objectSpace.sweep();
     m_objectSpace.shrink();
+    m_blockSnapshot.clear();
 
     sweepAllLogicallyEmptyWeakBlocks();

trunk/Source/JavaScriptCore/heap/Heap.h

@@ -166 +166 @@
 
     JS_EXPORT_PRIVATE void collectAllGarbageIfNotDoneRecently();
-    void collectAllGarbage() { collectAndSweep(FullCollection); }
-    JS_EXPORT_PRIVATE void collectAndSweep(HeapOperation collectionType = AnyCollection);
+    JS_EXPORT_PRIVATE void collectAllGarbage();
+
     bool shouldCollect();
     JS_EXPORT_PRIVATE void collect(HeapOperation collectionType = AnyCollection);

trunk/Source/JavaScriptCore/heap/MarkedBlock.cpp

@@ -164 +164 @@
             : specializedSweep<Marked, SweepOnly, callDestructors>();
     }
-
-    RELEASE_ASSERT_NOT_REACHED();
-    return FreeList();
 }
 

trunk/Source/JavaScriptCore/heap/MarkedBlock.h

@@ -2 +2 @@
  *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
- *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2016 Apple Inc. All rights reserved.
+ *  Copyright (C) 2003-2009, 2011, 2016 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
@@ -184 +184 @@
         static const size_t atomAlignmentMask = atomSize - 1;
 
+        // During allocation, we look for available space in free lists in blocks.
+        // If a block's utilization is sufficiently high (i.e. it's almost full),
+        // we want to remove that block as a candidate for allocating to reduce
+        // the likelihood of allocation having to take a slow path. When the
+        // block is in this state, we say that it is "Retired".
+        //
+        // A full GC can take a Retired blocks out of retirement. An eden GC
+        // will simply ignore Retired blocks (i.e. they will not be swept even
+        // if they no longer have live objects).
+
         enum BlockState { New, FreeListed, Allocated, Marked, Retired };
         template<bool callDestructors> FreeList sweepHelper(SweepMode = SweepOnly);

trunk/Source/JavaScriptCore/tools/JSDollarVMPrototype.cpp

@@ -130 +130 @@
     if (!ensureCurrentThreadOwnsJSLock(exec))
         return;
-    exec->heap()->collectAndSweep(EdenCollection);
+    exec->heap()->collect(EdenCollection);
 }