Title: [244506] trunk/Source/_javascript_Core
- Revision
- 244506
- Author
- ysuz...@apple.com
- Date
- 2019-04-22 11:35:04 -0700 (Mon, 22 Apr 2019)
Log Message
[JSC] Use volatile load to populate backing page in MarkedBlock::Footer instead of using holdLock
https://bugs.webkit.org/show_bug.cgi?id=197152
Reviewed by Saam Barati.
Emit volatile load instead of using holdLock to populate backing page in MarkedBlock::Footer.
* heap/BlockDirectory.cpp:
(JSC::BlockDirectory::isPagedOut):
* heap/MarkedBlock.h:
(JSC::MarkedBlock::populatePage const):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (244505 => 244506)
--- trunk/Source/_javascript_Core/ChangeLog 2019-04-22 18:30:16 UTC (rev 244505)
+++ trunk/Source/_javascript_Core/ChangeLog 2019-04-22 18:35:04 UTC (rev 244506)
@@ -1,5 +1,19 @@
2019-04-22 Yusuke Suzuki <ysuz...@apple.com>
+ [JSC] Use volatile load to populate backing page in MarkedBlock::Footer instead of using holdLock
+ https://bugs.webkit.org/show_bug.cgi?id=197152
+
+ Reviewed by Saam Barati.
+
+ Emit volatile load instead of using holdLock to populate backing page in MarkedBlock::Footer.
+
+ * heap/BlockDirectory.cpp:
+ (JSC::BlockDirectory::isPagedOut):
+ * heap/MarkedBlock.h:
+ (JSC::MarkedBlock::populatePage const):
+
+2019-04-22 Yusuke Suzuki <ysuz...@apple.com>
+
[JSC] useJIT should subsume useRegExpJIT
https://bugs.webkit.org/show_bug.cgi?id=197153
Modified: trunk/Source/_javascript_Core/heap/BlockDirectory.cpp (244505 => 244506)
--- trunk/Source/_javascript_Core/heap/BlockDirectory.cpp 2019-04-22 18:30:16 UTC (rev 244505)
+++ trunk/Source/_javascript_Core/heap/BlockDirectory.cpp 2019-04-22 18:35:04 UTC (rev 244506)
@@ -61,11 +61,8 @@
{
unsigned itersSinceLastTimeCheck = 0;
for (auto* block : m_blocks) {
- if (block) {
- // We take and drop the lock as a way of touching that page of memory.
- // FIXME: should we instead do a cheaper thing like a volatile load in the page?
- (void) holdLock(block->block().lock());
- }
+ if (block)
+ block->block().populatePage();
++itersSinceLastTimeCheck;
if (itersSinceLastTimeCheck >= Heap::s_timeCheckResolution) {
MonotonicTime currentTime = MonotonicTime::now();
Modified: trunk/Source/_javascript_Core/heap/MarkedBlock.h (244505 => 244506)
--- trunk/Source/_javascript_Core/heap/MarkedBlock.h 2019-04-22 18:30:16 UTC (rev 244505)
+++ trunk/Source/_javascript_Core/heap/MarkedBlock.h 2019-04-22 18:35:04 UTC (rev 244506)
@@ -374,6 +374,11 @@
CountingLock& lock() { return footer().m_lock; }
Subspace* subspace() const { return footer().m_subspace; }
+
+ void populatePage() const
+ {
+ *bitwise_cast<volatile uint8_t*>(&footer());
+ }
static constexpr size_t offsetOfFooter = endAtom * atomSize;
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