[webkit-changes] [233714] trunk/Source/JavaScriptCore

Tue, 10 Jul 2018 17:17:31 -0700

Title: [233714] trunk/Source/_javascript_Core
Revision
233714
Author
fpi...@apple.com
Date
2018-07-10 17:16:07 -0700 (Tue, 10 Jul 2018)

Log Message

Change the reoptimization backoff base to 1.3 from 2
https://bugs.webkit.org/show_bug.cgi?id=187540

Reviewed by Saam Barati.
        
I have data that hints at this being a speed-up on JetStream, ARES-6, and Speedometer2.
        
I also have data that hints that a backoff base of 1 might be even better, but I think that
we want to keep *some* backoff in case we find ourselves in an unmitigated recomp loop.

* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::reoptimizationRetryCounter const):
(JSC::CodeBlock::countReoptimization):
(JSC::CodeBlock::adjustedCounterValue):
* runtime/Options.cpp:
(JSC::recomputeDependentOptions):
* runtime/Options.h:

Modified Paths

Diff

Modified: trunk/Source/_javascript_Core/ChangeLog (233713 => 233714)


--- trunk/Source/_javascript_Core/ChangeLog	2018-07-11 00:09:11 UTC (rev 233713)
+++ trunk/Source/_javascript_Core/ChangeLog	2018-07-11 00:16:07 UTC (rev 233714)
@@ -1,3 +1,23 @@
+2018-07-10  Filip Pizlo  <fpi...@apple.com>
+
+        Change the reoptimization backoff base to 1.3 from 2
+        https://bugs.webkit.org/show_bug.cgi?id=187540
+
+        Reviewed by Saam Barati.
+        
+        I have data that hints at this being a speed-up on JetStream, ARES-6, and Speedometer2.
+        
+        I also have data that hints that a backoff base of 1 might be even better, but I think that
+        we want to keep *some* backoff in case we find ourselves in an unmitigated recomp loop.
+
+        * bytecode/CodeBlock.cpp:
+        (JSC::CodeBlock::reoptimizationRetryCounter const):
+        (JSC::CodeBlock::countReoptimization):
+        (JSC::CodeBlock::adjustedCounterValue):
+        * runtime/Options.cpp:
+        (JSC::recomputeDependentOptions):
+        * runtime/Options.h:
+
 2018-07-10  Mark Lam  <mark....@apple.com>
 
         [32-bit JSC tests] ASSERTION FAILED: !butterfly->propertyStorage()[-I - 1].get() under JSC::ObjectInitializationScope::verifyPropertiesAreInitialized.

Modified: trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp (233713 => 233714)


--- trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp	2018-07-11 00:09:11 UTC (rev 233713)
+++ trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp	2018-07-11 00:16:07 UTC (rev 233714)
@@ -2136,7 +2136,6 @@
 unsigned CodeBlock::reoptimizationRetryCounter() const
 {
 #if ENABLE(JIT)
-    ASSERT(m_reoptimizationRetryCounter <= Options::reoptimizationRetryCounterMax());
     return m_reoptimizationRetryCounter;
 #else
     return 0;
@@ -2174,8 +2173,6 @@
 void CodeBlock::countReoptimization()
 {
     m_reoptimizationRetryCounter++;
-    if (m_reoptimizationRetryCounter > Options::reoptimizationRetryCounterMax())
-        m_reoptimizationRetryCounter = Options::reoptimizationRetryCounterMax();
 }
 
 unsigned CodeBlock::numberOfDFGCompiles()
@@ -2294,7 +2291,7 @@
     return clipThreshold(
         static_cast<double>(desiredThreshold) *
         optimizationThresholdScalingFactor() *
-        (1 << reoptimizationRetryCounter()));
+        pow(Options::reoptimizationBackoffBase(), reoptimizationRetryCounter()));
 }
 
 bool CodeBlock::checkIfOptimizationThresholdReached()

Modified: trunk/Source/_javascript_Core/runtime/Options.cpp (233713 => 233714)


--- trunk/Source/_javascript_Core/runtime/Options.cpp	2018-07-11 00:09:11 UTC (rev 233713)
+++ trunk/Source/_javascript_Core/runtime/Options.cpp	2018-07-11 00:16:07 UTC (rev 233714)
@@ -471,18 +471,6 @@
     if (Options::alwaysUseShadowChicken())
         Options::maximumInliningDepth() = 1;
 
-    // Compute the maximum value of the reoptimization retry counter. This is simply
-    // the largest value at which we don't overflow the execute counter, when using it
-    // to left-shift the execution counter by this amount. Currently the value ends
-    // up being 18, so this loop is not so terrible; it probably takes up ~100 cycles
-    // total on a 32-bit processor.
-    Options::reoptimizationRetryCounterMax() = 0;
-    while ((static_cast<int64_t>(Options::thresholdForOptimizeAfterLongWarmUp()) << (Options::reoptimizationRetryCounterMax() + 1)) <= static_cast<int64_t>(std::numeric_limits<int32_t>::max()))
-        Options::reoptimizationRetryCounterMax()++;
-
-    ASSERT((static_cast<int64_t>(Options::thresholdForOptimizeAfterLongWarmUp()) << Options::reoptimizationRetryCounterMax()) > 0);
-    ASSERT((static_cast<int64_t>(Options::thresholdForOptimizeAfterLongWarmUp()) << Options::reoptimizationRetryCounterMax()) <= static_cast<int64_t>(std::numeric_limits<int32_t>::max()));
-
 #if !defined(NDEBUG)
     if (Options::maxSingleAllocationSize())
         fastSetMaxSingleAllocationSize(Options::maxSingleAllocationSize());

Modified: trunk/Source/_javascript_Core/runtime/Options.h (233713 => 233714)


--- trunk/Source/_javascript_Core/runtime/Options.h	2018-07-11 00:09:11 UTC (rev 233713)
+++ trunk/Source/_javascript_Core/runtime/Options.h	2018-07-11 00:16:07 UTC (rev 233714)
@@ -361,7 +361,7 @@
     v(unsigned, osrExitCountForReoptimization, 100, Normal, nullptr) \
     v(unsigned, osrExitCountForReoptimizationFromLoop, 5, Normal, nullptr) \
     \
-    v(unsigned, reoptimizationRetryCounterMax, 0, Normal, nullptr)  \
+    v(double, reoptimizationBackoffBase, 1.3, Normal, nullptr) \
     \
     v(unsigned, minimumOptimizationDelay, 1, Normal, nullptr) \
     v(unsigned, maximumOptimizationDelay, 5, Normal, nullptr) \

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