Changeset 243389 in webkit

Timestamp:

Mar 22, 2019, 10:43:29 AM (7 years ago)

Author:

msaboff@apple.com

Message:

[BMalloc] No need to delay deallocating chunks based on recent use
​https://bugs.webkit.org/show_bug.cgi?id=196121

Reviewed by Mark Lam.

The "used since last scavenge" logic is not needed for small chunks since their memory isn't decommitted directly.
We can deallocate small chunks immediately as that adds them to the LargeRange free list. That free list employs the
"used since last scavenge" logic before the scavenger decommits the backing memory.

• bmalloc/Chunk.h:

(bmalloc::Chunk::usedSinceLastScavenge): Deleted.
(bmalloc::Chunk::clearUsedSinceLastScavenge): Deleted.
(bmalloc::Chunk::setUsedSinceLastScavenge): Deleted.

• bmalloc/Heap.cpp:

(bmalloc::Heap::scavenge):
(bmalloc::Heap::allocateSmallPage):

Location:

trunk/Source/bmalloc

Files:

• ChangeLog (modified) (1 diff)
• bmalloc/Chunk.h (modified) (2 diffs)
• bmalloc/Heap.cpp (modified) (2 diffs)

trunk/Source/bmalloc/ChangeLog

@@ +1 @@
+2019-03-21  Michael Saboff  <msaboff@apple.com>
+
+        [BMalloc] No need to delay deallocating chunks based on recent use
+        https://bugs.webkit.org/show_bug.cgi?id=196121
+
+        Reviewed by Mark Lam.
+
+        The "used since last scavenge" logic is not needed for small chunks since their memory isn't decommitted directly.
+        We can deallocate small chunks immediately as that adds them to the LargeRange free list.  That free list employs the
+        "used since last scavenge" logic before the scavenger decommits the backing memory.
+
+        * bmalloc/Chunk.h:
+        (bmalloc::Chunk::usedSinceLastScavenge): Deleted.
+        (bmalloc::Chunk::clearUsedSinceLastScavenge): Deleted.
+        (bmalloc::Chunk::setUsedSinceLastScavenge): Deleted.
+        * bmalloc/Heap.cpp:
+        (bmalloc::Heap::scavenge):
+        (bmalloc::Heap::allocateSmallPage):
+
 2019-03-21  Brady Eidson  <beidson@apple.com>
 

trunk/Source/bmalloc/bmalloc/Chunk.h

@@ -46 +46 @@
     unsigned refCount() { return m_refCount; }
 
-    bool usedSinceLastScavenge() { return m_usedSinceLastScavenge; }
-    void clearUsedSinceLastScavenge() { m_usedSinceLastScavenge = false; }
-    void setUsedSinceLastScavenge() { m_usedSinceLastScavenge = true; }
-
     size_t offset(void*);
 
@@ -64 +60 @@
 private:
     size_t m_refCount { };
-    bool m_usedSinceLastScavenge: 1;
     List<SmallPage> m_freePages { };
 

trunk/Source/bmalloc/bmalloc/Heap.cpp

@@ -203 +203 @@
 
     for (auto& list : m_chunkCache) {
-        for (auto iter = list.begin(); iter != list.end(); ) {
-            Chunk* chunk = *iter;
-            if (chunk->usedSinceLastScavenge()) {
-                chunk->clearUsedSinceLastScavenge();
-                deferredDecommits++;
-                ++iter;
-                continue;
-            }
-            ++iter;
-            list.remove(chunk);
-            deallocateSmallChunk(chunk, &list - &m_chunkCache[0]);
-        }
+        while (!list.isEmpty())
+            deallocateSmallChunk(list.pop(), &list - &m_chunkCache[0]);
     }
 
@@ -317 +307 @@
 
         chunk->ref();
-        chunk->setUsedSinceLastScavenge();
 
         SmallPage* page = chunk->freePages().pop();