Changeset 233378 in webkit

Timestamp:

Jun 29, 2018 5:05:36 PM (6 years ago)

Author:

sbarati@apple.com

Message:

Don't use tracePoints in JS/Wasm entry
​https://bugs.webkit.org/show_bug.cgi?id=187196

Reviewed by Mark Lam.

This puts VM entry and Wasm entry tracePoints behind a runtime
option. This is a ~4x speedup on a soon to be released Wasm
benchmark. tracePoints should basically never run more than 50
times a second. Entering the VM and entering Wasm are user controlled,
and can happen hundreds of thousands of times in a second. Depending
on how the Wasm/JS code is structured, this can be disastrous for
performance.

• runtime/Options.h:
• runtime/VMEntryScope.cpp:

(JSC::VMEntryScope::VMEntryScope):
(JSC::VMEntryScope::~VMEntryScope):

• wasm/WasmBBQPlan.cpp:

(JSC::Wasm::BBQPlan::compileFunctions):

• wasm/js/WebAssemblyFunction.cpp:

(JSC::callWebAssemblyFunction):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/Options.h (modified) (1 diff)
• runtime/VMEntryScope.cpp (modified) (2 diffs)
• wasm/WasmBBQPlan.cpp (modified) (1 diff)
• wasm/js/WebAssemblyFunction.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2018-06-29  Saam Barati  <sbarati@apple.com>
+
+        Don't use tracePoints in JS/Wasm entry
+        https://bugs.webkit.org/show_bug.cgi?id=187196
+
+        Reviewed by Mark Lam.
+
+        This puts VM entry and Wasm entry tracePoints behind a runtime
+        option. This is a ~4x speedup on a soon to be released Wasm
+        benchmark. tracePoints should basically never run more than 50
+        times a second. Entering the VM and entering Wasm are user controlled,
+        and can happen hundreds of thousands of times in a second. Depending
+        on how the Wasm/JS code is structured, this can be disastrous for
+        performance.
+
+        * runtime/Options.h:
+        * runtime/VMEntryScope.cpp:
+        (JSC::VMEntryScope::VMEntryScope):
+        (JSC::VMEntryScope::~VMEntryScope):
+        * wasm/WasmBBQPlan.cpp:
+        (JSC::Wasm::BBQPlan::compileFunctions):
+        * wasm/js/WebAssemblyFunction.cpp:
+        (JSC::callWebAssemblyFunction):
+
 2018-06-29  Saam Barati  <sbarati@apple.com>
 

trunk/Source/JavaScriptCore/runtime/Options.h

@@ -513 +513 @@
     v(bool, useArrayAllocationProfiling, true, Normal, "If true, we will use our normal array allocation profiling. If false, the allocation profile will always claim to be undecided.") \
     v(bool, forcePolyProto, false, Normal, "If true, create_this will always create an object with a poly proto structure.") \
-    v(bool, forceMiniVMMode, false, Normal, "If true, it will force mini VM mode on.")
+    v(bool, forceMiniVMMode, false, Normal, "If true, it will force mini VM mode on.") \
+    v(bool, useTracePoints, false, Normal, nullptr)
 
 

trunk/Source/JavaScriptCore/runtime/VMEntryScope.cpp

@@ -58 +58 @@
             samplingProfiler->noticeVMEntry();
 #endif
-        tracePoint(VMEntryScopeStart);
+        if (Options::useTracePoints())
+            tracePoint(VMEntryScopeStart);
     }
 
@@ -74 +75 @@
         return;
 
-    tracePoint(VMEntryScopeEnd);
+    if (Options::useTracePoints())
+        tracePoint(VMEntryScopeEnd);
     
     if (m_vm.watchdog())

trunk/Source/JavaScriptCore/wasm/WasmBBQPlan.cpp

@@ -236 +236 @@
         return;
 
-    TraceScope traceScope(WebAssemblyCompileStart, WebAssemblyCompileEnd);
+    std::optional<TraceScope> traceScope;
+    if (Options::useTracePoints())
+        traceScope.emplace(WebAssemblyCompileStart, WebAssemblyCompileEnd);
     ThreadCountHolder holder(*this);
 

trunk/Source/JavaScriptCore/wasm/js/WebAssemblyFunction.cpp

@@ -80 +80 @@
     }
 
-    TraceScope traceScope(WebAssemblyExecuteStart, WebAssemblyExecuteEnd);
+    std::optional<TraceScope> traceScope;
+    if (Options::useTracePoints())
+        traceScope.emplace(WebAssemblyExecuteStart, WebAssemblyExecuteEnd);
 
     Vector<JSValue> boxedArgs;