- Record cache hit rates at different levels in the compilation cache...

src/compilation-cache.cc

 // Copyright 2008 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 18 matching lines @@
 
 #include "compilation-cache.h"
 
 namespace v8 {
 namespace internal {
 
 enum {
   // The number of script generations tell how many GCs a script can
   // survive in the compilation cache, before it will be flushed if it
   // hasn't been used.
-  NUMBER_OF_SCRIPT_GENERATIONS = 5,
+  NUMBER_OF_SCRIPT_GENERATIONS = 8,
 
   // The compilation cache consists of tables - one for each entry
   // kind plus extras for the script generations.
   NUMBER_OF_TABLE_ENTRIES =
       CompilationCache::LAST_ENTRY + NUMBER_OF_SCRIPT_GENERATIONS
 };
 
 
 // Current enable state of the compilation cache.
 static bool enabled = true;
@@ skipping 118 matching lines @@
         if (HasOrigin(boilerplate, name, line_offset, column_offset)) {
           result = *boilerplate;
           break;
         }
       }
       // Go to the next generation.
       generation++;
     }
   }
 
+  static void* script_histogram_ = StatsTable::CreateHistogram(
+      "V8.ScriptCache",
+      0,
+      NUMBER_OF_SCRIPT_GENERATIONS,
+      NUMBER_OF_SCRIPT_GENERATIONS + 1);
+
+  if (script_histogram_ != NULL) {
+    // The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
+    StatsTable::AddHistogramSample(script_histogram_, generation - SCRIPT);
+  }
+
   // Once outside the manacles of the handle scope, we need to recheck
   // to see if we actually found a cached script. If so, we return a
   // handle created in the caller's handle scope.
   if (result != NULL) {
     Handle<JSFunction> boilerplate(JSFunction::cast(result));
     ASSERT(HasOrigin(boilerplate, name, line_offset, column_offset));
     // If the script was found in a later generation, we promote it to
     // the first generation to let it survive longer in the cache.
     if (generation != SCRIPT) PutScript(source, boilerplate);
     Counters::compilation_cache_hits.Increment();
@@ skipping 109 matching lines @@
 }
 
 
 void CompilationCache::Disable() {
   enabled = false;
   Clear();
 }
 
 
 } }  // namespace v8::internal