Support profiling based on linux kernel performance events.

src/flag-definitions.h

 // 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 394 matching lines @@
 DEFINE_bool(prof_lazy, false,
             "Used with --prof, only does sampling and logging"
             " when profiler is active (implies --noprof_auto).")
 DEFINE_bool(prof_browser_mode, true,
             "Used with --prof, turns on browser-compatible mode for profiling.")
 DEFINE_bool(log_regexp, false, "Log regular expression execution.")
 DEFINE_bool(sliding_state_window, false,
             "Update sliding state window counters.")
 DEFINE_string(logfile, "v8.log", "Specify the name of the log file.")
 DEFINE_bool(oprofile, false, "Enable JIT agent for OProfile.")
+DEFINE_bool(ll_prof, false, "Enable low-level linux profiler.")
 
 //
 // Heap protection flags
 // Using heap protection requires ENABLE_LOGGING_AND_PROFILING as well.
 //
 #ifdef ENABLE_HEAP_PROTECTION
 #undef FLAG
 #define FLAG FLAG_FULL
 
 DEFINE_bool(protect_heap, false,
@@ skipping 24 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META