Title: [252621] trunk/Source/bmalloc
- Revision
- 252621
- Author
- [email protected]
- Date
- 2019-11-18 19:29:12 -0800 (Mon, 18 Nov 2019)
Log Message
[bmalloc] Some chunks have unused region in the tail of its memory block.
https://bugs.webkit.org/show_bug.cgi?id=204286
Reviewed by Yusuke Suzuki.
When chunk is initialized, some amount of memory are not used and be kept untouched until its end.
This patch tries to decommit those region at the end of initialization.
For instance, think about the case that the pageClass is 5. Then pageSize is 24k. With this pageSize,
a chunk can hold 42 pages and its size is 24k * 42 = 1008k which is smaller than chunkSize = 1024k.
Here is the complete result:
page page page
class size count remainings
----------------------------------
0 4kB 256 0
1 8kB 128 0
2 12kB 85 4kB
3 16kB 64 0
4 20kB 51 4kB
5 24kB 42 16kB
6 28kB 36 16kB
7 32kB 32 0
8 36kB 28 16kB
9 40kB 25 24kB
10 44kB 23 12kB
11 48kB 21 16kB
12 52kB 19 36kB
13 56kB 18 16kB
14 60kB 17 4kB
15 64kB 16 0
Tested on Mac testmem and result is almost same or in error margin.
Before: After:
end score: 8.5425 MB end score: 8.5127 MB
peak score: 8.7997 MB peak score: 8.7884 MB
total memory score: 8.6702 MB total memory score: 8.6495 MB
time score: 668.19 ms time score: 666.27 ms
* bmalloc/Chunk.h:
(bmalloc::Chunk::metadataSize):
(bmalloc::forEachPage):
* bmalloc/Heap.cpp:
(bmalloc::Heap::allocateSmallChunk):
Modified Paths
Diff
Modified: trunk/Source/bmalloc/ChangeLog (252620 => 252621)
--- trunk/Source/bmalloc/ChangeLog 2019-11-19 03:16:44 UTC (rev 252620)
+++ trunk/Source/bmalloc/ChangeLog 2019-11-19 03:29:12 UTC (rev 252621)
@@ -1,3 +1,51 @@
+2019-11-18 Basuke Suzuki <[email protected]>
+
+ [bmalloc] Some chunks have unused region in the tail of its memory block.
+ https://bugs.webkit.org/show_bug.cgi?id=204286
+
+ Reviewed by Yusuke Suzuki.
+
+ When chunk is initialized, some amount of memory are not used and be kept untouched until its end.
+ This patch tries to decommit those region at the end of initialization.
+
+ For instance, think about the case that the pageClass is 5. Then pageSize is 24k. With this pageSize,
+ a chunk can hold 42 pages and its size is 24k * 42 = 1008k which is smaller than chunkSize = 1024k.
+ Here is the complete result:
+
+ page page page
+ class size count remainings
+ ----------------------------------
+ 0 4kB 256 0
+ 1 8kB 128 0
+ 2 12kB 85 4kB
+ 3 16kB 64 0
+ 4 20kB 51 4kB
+ 5 24kB 42 16kB
+ 6 28kB 36 16kB
+ 7 32kB 32 0
+ 8 36kB 28 16kB
+ 9 40kB 25 24kB
+ 10 44kB 23 12kB
+ 11 48kB 21 16kB
+ 12 52kB 19 36kB
+ 13 56kB 18 16kB
+ 14 60kB 17 4kB
+ 15 64kB 16 0
+
+ Tested on Mac testmem and result is almost same or in error margin.
+
+ Before: After:
+ end score: 8.5425 MB end score: 8.5127 MB
+ peak score: 8.7997 MB peak score: 8.7884 MB
+ total memory score: 8.6702 MB total memory score: 8.6495 MB
+ time score: 668.19 ms time score: 666.27 ms
+
+ * bmalloc/Chunk.h:
+ (bmalloc::Chunk::metadataSize):
+ (bmalloc::forEachPage):
+ * bmalloc/Heap.cpp:
+ (bmalloc::Heap::allocateSmallChunk):
+
2019-11-15 Basuke Suzuki <[email protected]>
[bmalloc] The tracking of freeableMemory of Heap doesn't count Chunk's metadata size.
Modified: trunk/Source/bmalloc/bmalloc/Chunk.h (252620 => 252621)
--- trunk/Source/bmalloc/bmalloc/Chunk.h 2019-11-19 03:16:44 UTC (rev 252620)
+++ trunk/Source/bmalloc/bmalloc/Chunk.h 2019-11-19 03:29:12 UTC (rev 252621)
@@ -38,6 +38,7 @@
class Chunk : public ListNode<Chunk> {
public:
static Chunk* get(void*);
+ static size_t metadataSize(size_t pageSize);
Chunk(size_t pageSize);
@@ -73,13 +74,16 @@
}
};
-template<typename Function> void forEachPage(Chunk* chunk, size_t pageSize, Function function)
+inline size_t Chunk::metadataSize(size_t pageSize)
{
// We align to at least the page size so we can service aligned allocations
// at equal and smaller powers of two, and also so we can vmDeallocatePhysicalPages().
- size_t metadataSize = roundUpToMultipleOfNonPowerOfTwo(pageSize, sizeof(Chunk));
+ return roundUpToMultipleOfNonPowerOfTwo(pageSize, sizeof(Chunk));
+}
- Object begin(chunk, metadataSize);
+template<typename Function> void forEachPage(Chunk* chunk, size_t pageSize, Function function)
+{
+ Object begin(chunk, Chunk::metadataSize(pageSize));
Object end(chunk, chunkSize);
for (auto it = begin; it + pageSize <= end; it = it + pageSize)
Modified: trunk/Source/bmalloc/bmalloc/Heap.cpp (252620 => 252621)
--- trunk/Source/bmalloc/bmalloc/Heap.cpp 2019-11-19 03:16:44 UTC (rev 252620)
+++ trunk/Source/bmalloc/bmalloc/Heap.cpp 2019-11-19 03:29:12 UTC (rev 252621)
@@ -286,7 +286,11 @@
});
m_freeableMemory += accountedInFreeable;
-
+
+ auto decommitSize = chunkSize - Chunk::metadataSize(pageSize) - accountedInFreeable;
+ if (decommitSize > 0)
+ vmDeallocatePhysicalPagesSloppy(Chunk::get(chunk)->address(chunkSize - decommitSize), decommitSize);
+
m_scavenger->schedule(0);
return chunk;
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