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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/190217">190217</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2015-09-24 13:13:07 -0700 (Thu, 24 Sep 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Remove special case code for the no-parallel-GC case
https://bugs.webkit.org/show_bug.cgi?id=149512
Reviewed by Mark Lam.
Make serial GC just a parallel GC where the helper threads don't do anything. Also make the
idle thread calculation a bit more explicit.
The main outcome is that we no longer use Options::numberOfGCMarkers() as much, so the code is
resilient against the number of GC markers changing.
* heap/Heap.h:
* heap/SlotVisitor.cpp:
(JSC::SlotVisitor::donateKnownParallel):
(JSC::SlotVisitor::drain):
(JSC::SlotVisitor::drainFromShared):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapHeaph">trunk/Source/JavaScriptCore/heap/Heap.h</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapSlotVisitorcpp">trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (190216 => 190217)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-09-24 19:36:17 UTC (rev 190216)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-09-24 20:13:07 UTC (rev 190217)
</span><span class="lines">@@ -1,5 +1,24 @@
</span><span class="cx"> 2015-09-23 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><ins>+ Remove special case code for the no-parallel-GC case
+ https://bugs.webkit.org/show_bug.cgi?id=149512
+
+ Reviewed by Mark Lam.
+
+ Make serial GC just a parallel GC where the helper threads don't do anything. Also make the
+ idle thread calculation a bit more explicit.
+
+ The main outcome is that we no longer use Options::numberOfGCMarkers() as much, so the code is
+ resilient against the number of GC markers changing.
+
+ * heap/Heap.h:
+ * heap/SlotVisitor.cpp:
+ (JSC::SlotVisitor::donateKnownParallel):
+ (JSC::SlotVisitor::drain):
+ (JSC::SlotVisitor::drainFromShared):
+
+2015-09-23 Filip Pizlo <fpizlo@apple.com>
+
</ins><span class="cx"> PolymorphicAccess should remember that it checked an ObjectPropertyCondition with a check on some structure
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=149514
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapHeaph"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/Heap.h (190216 => 190217)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/Heap.h 2015-09-24 19:36:17 UTC (rev 190216)
+++ trunk/Source/JavaScriptCore/heap/Heap.h 2015-09-24 20:13:07 UTC (rev 190217)
</span><span class="lines">@@ -428,6 +428,7 @@
</span><span class="cx"> Condition m_markingConditionVariable;
</span><span class="cx"> MarkStackArray m_sharedMarkStack;
</span><span class="cx"> unsigned m_numberOfActiveParallelMarkers { 0 };
</span><ins>+ unsigned m_numberOfWaitingParallelMarkers { 0 };
</ins><span class="cx"> bool m_parallelMarkersShouldExit { false };
</span><span class="cx">
</span><span class="cx"> Lock m_opaqueRootsMutex;
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapSlotVisitorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp (190216 => 190217)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp 2015-09-24 19:36:17 UTC (rev 190216)
+++ trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp 2015-09-24 20:13:07 UTC (rev 190217)
</span><span class="lines">@@ -147,8 +147,7 @@
</span><span class="cx"> // Otherwise, assume that a thread will go idle soon, and donate.
</span><span class="cx"> m_stack.donateSomeCellsTo(m_heap.m_sharedMarkStack);
</span><span class="cx">
</span><del>- if (m_heap.m_numberOfActiveParallelMarkers < Options::numberOfGCMarkers())
- m_heap.m_markingConditionVariable.notifyAll();
</del><ins>+ m_heap.m_markingConditionVariable.notifyAll();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void SlotVisitor::drain()
</span><span class="lines">@@ -156,23 +155,14 @@
</span><span class="cx"> StackStats::probe();
</span><span class="cx"> ASSERT(m_isInParallelMode);
</span><span class="cx">
</span><del>- if (Options::numberOfGCMarkers() > 1) {
- while (!m_stack.isEmpty()) {
- m_stack.refill();
- for (unsigned countdown = Options::minimumNumberOfScansBetweenRebalance(); m_stack.canRemoveLast() && countdown--;)
- visitChildren(*this, m_stack.removeLast());
- donateKnownParallel();
- }
-
- mergeOpaqueRootsIfNecessary();
- return;
- }
-
</del><span class="cx"> while (!m_stack.isEmpty()) {
</span><span class="cx"> m_stack.refill();
</span><del>- while (m_stack.canRemoveLast())
</del><ins>+ for (unsigned countdown = Options::minimumNumberOfScansBetweenRebalance(); m_stack.canRemoveLast() && countdown--;)
</ins><span class="cx"> visitChildren(*this, m_stack.removeLast());
</span><ins>+ donateKnownParallel();
</ins><span class="cx"> }
</span><ins>+
+ mergeOpaqueRootsIfNecessary();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void SlotVisitor::drainFromShared(SharedDrainMode sharedDrainMode)
</span><span class="lines">@@ -182,18 +172,6 @@
</span><span class="cx">
</span><span class="cx"> ASSERT(Options::numberOfGCMarkers());
</span><span class="cx">
</span><del>- bool shouldBeParallel;
-
- shouldBeParallel = Options::numberOfGCMarkers() > 1;
-
- if (!shouldBeParallel) {
- // This call should be a no-op.
- ASSERT_UNUSED(sharedDrainMode, sharedDrainMode == MasterDrain);
- ASSERT(m_stack.isEmpty());
- ASSERT(m_heap.m_sharedMarkStack.isEmpty());
- return;
- }
-
</del><span class="cx"> {
</span><span class="cx"> std::lock_guard<Lock> lock(m_heap.m_markingMutex);
</span><span class="cx"> m_heap.m_numberOfActiveParallelMarkers++;
</span><span class="lines">@@ -202,6 +180,7 @@
</span><span class="cx"> {
</span><span class="cx"> std::unique_lock<Lock> lock(m_heap.m_markingMutex);
</span><span class="cx"> m_heap.m_numberOfActiveParallelMarkers--;
</span><ins>+ m_heap.m_numberOfWaitingParallelMarkers++;
</ins><span class="cx">
</span><span class="cx"> // How we wait differs depending on drain mode.
</span><span class="cx"> if (sharedDrainMode == MasterDrain) {
</span><span class="lines">@@ -209,7 +188,8 @@
</span><span class="cx"> // for us to do.
</span><span class="cx"> while (true) {
</span><span class="cx"> // Did we reach termination?
</span><del>- if (!m_heap.m_numberOfActiveParallelMarkers && m_heap.m_sharedMarkStack.isEmpty()) {
</del><ins>+ if (!m_heap.m_numberOfActiveParallelMarkers
+ && m_heap.m_sharedMarkStack.isEmpty()) {
</ins><span class="cx"> // Let any sleeping slaves know it's time for them to return;
</span><span class="cx"> m_heap.m_markingConditionVariable.notifyAll();
</span><span class="cx"> return;
</span><span class="lines">@@ -226,19 +206,26 @@
</span><span class="cx"> ASSERT(sharedDrainMode == SlaveDrain);
</span><span class="cx">
</span><span class="cx"> // Did we detect termination? If so, let the master know.
</span><del>- if (!m_heap.m_numberOfActiveParallelMarkers && m_heap.m_sharedMarkStack.isEmpty())
</del><ins>+ if (!m_heap.m_numberOfActiveParallelMarkers
+ && m_heap.m_sharedMarkStack.isEmpty())
</ins><span class="cx"> m_heap.m_markingConditionVariable.notifyAll();
</span><span class="cx">
</span><del>- m_heap.m_markingConditionVariable.wait(lock, [this] { return !m_heap.m_sharedMarkStack.isEmpty() || m_heap.m_parallelMarkersShouldExit; });
</del><ins>+ m_heap.m_markingConditionVariable.wait(
+ lock,
+ [this] {
+ return !m_heap.m_sharedMarkStack.isEmpty()
+ || m_heap.m_parallelMarkersShouldExit;
+ });
</ins><span class="cx">
</span><span class="cx"> // Is the current phase done? If so, return from this function.
</span><span class="cx"> if (m_heap.m_parallelMarkersShouldExit)
</span><span class="cx"> return;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- size_t idleThreadCount = Options::numberOfGCMarkers() - m_heap.m_numberOfActiveParallelMarkers;
- m_stack.stealSomeCellsFrom(m_heap.m_sharedMarkStack, idleThreadCount);
</del><ins>+ m_stack.stealSomeCellsFrom(
+ m_heap.m_sharedMarkStack, m_heap.m_numberOfWaitingParallelMarkers);
</ins><span class="cx"> m_heap.m_numberOfActiveParallelMarkers++;
</span><ins>+ m_heap.m_numberOfWaitingParallelMarkers--;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> drain();
</span></span></pre>
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