Track how much time the compiler thread spends doing useful work.

src/optimizing-compiler-thread.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 25 matching lines @@
 namespace v8 {
 namespace internal {
 
 
 void OptimizingCompilerThread::Run() {
 #ifdef DEBUG
   thread_id_ = ThreadId::Current().ToInteger();
 #endif
   Isolate::SetIsolateThreadLocals(isolate_, NULL);
 
+  int64_t epoch = 0;
+  if (FLAG_trace_parallel_recompilation) epoch = OS::Ticks();
+
   while (true) {
     input_queue_semaphore_->Wait();
     if (Acquire_Load(&stop_thread_)) {
       stop_semaphore_->Signal();
+      if (FLAG_trace_parallel_recompilation) {
+        time_spent_total_ = OS::Ticks() - epoch;
+      }
       return;
     }
 
+    int64_t compiling_start = 0;
+    if (FLAG_trace_parallel_recompilation) compiling_start = OS::Ticks();
+
     Heap::RelocationLock relocation_lock(isolate_->heap());
     OptimizingCompiler* optimizing_compiler = NULL;
     input_queue_.Dequeue(&optimizing_compiler);
     Barrier_AtomicIncrement(&queue_length_, static_cast<Atomic32>(-1));
 
     ASSERT(!optimizing_compiler->info()->closure()->IsOptimized());
 
     OptimizingCompiler::Status status = optimizing_compiler->OptimizeGraph();
     ASSERT(status != OptimizingCompiler::FAILED);
     // Prevent an unused-variable error in release mode.
     (void) status;

[Yang, 2012/07/20 08:21:38]

Change this to USE(status)

 
     output_queue_.Enqueue(optimizing_compiler);
     isolate_->stack_guard()->RequestCodeReadyEvent();
+
+    if (FLAG_trace_parallel_recompilation) {
+      time_spent_compiling_ += OS::Ticks() - compiling_start;
+    }
   }
 }
 
 
 void OptimizingCompilerThread::Stop() {
   Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
   input_queue_semaphore_->Signal();
   stop_semaphore_->Wait();
+
+  if (FLAG_trace_parallel_recompilation) {
+    double compile_time = static_cast<double>(time_spent_compiling_);
+    double total_time = static_cast<double>(time_spent_total_);
+    double percentage = (compile_time * 100) / total_time;
+    PrintF("  ** Compiler thread did %.2f%% useful work\n", percentage);
+  }
 }
 
 
 void OptimizingCompilerThread::InstallOptimizedFunctions() {
   HandleScope handle_scope(isolate_);
   int functions_installed = 0;
   while (!output_queue_.IsEmpty()) {
     OptimizingCompiler* compiler = NULL;
     output_queue_.Dequeue(&compiler);
     Compiler::InstallOptimizedCode(compiler);
@@ skipping 13 matching lines @@
 
 #ifdef DEBUG
 bool OptimizingCompilerThread::IsOptimizerThread() {
   if (!FLAG_parallel_recompilation) return false;
   return ThreadId::Current().ToInteger() == thread_id_;
 }
 #endif
 
 
 } }  // namespace v8::internal