Implement resource-saving mode of Profiler.

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 317 matching lines @@
 DEFINE_bool(log_code, false,
             "Log code events to the log file without profiling.")
 DEFINE_bool(log_gc, false,
             "Log heap samples on garbage collection for the hp2ps tool.")
 DEFINE_bool(log_handles, false, "Log global handle events.")
 DEFINE_bool(log_state_changes, false, "Log state changes.")
 DEFINE_bool(log_suspect, false, "Log suspect operations.")
 DEFINE_bool(prof, false,
             "Log statistical profiling information (implies --log-code).")
 DEFINE_bool(prof_auto, true,
             "Used with --prof, starts profiling automatically")

[Søren Thygesen Gjesse, 2009/05/25 07:09:15]

Do we need both --prof-auto and --prof-lazy. With your last change where logging
can be initiated by getting all the functions in the heap I don't see a reason
for logging and sampling if not really profiling. Am I missing something here?
If it makes sense to consolidate --prof-auto and --prof-lazy in some way you can
do that in a new change.

[Mikhail Naganov, 2009/05/25 08:23:43]

Currently, we have several differences in results of "traditional" compiler / gc
logging vs. heap traversal, the differences can be seen in the code of
"AreFuncNamesEqual" and "AreEntitiesEqual" functions from test-log.cc. They only
related to native and internal code, so they are irrelevant to web app
developers, but may make sense for V8 developers. That's why I'll prefer to
leave "traditional" profiling logging for some time until I figure out how to
handle this better.

+DEFINE_bool(prof_lazy, false,
+            "Used with --prof, only does sampling and logging"
+            " when profiler is active (implies --noprof_auto).")
 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.")
 
 //
 // Heap protection flags
 // Using heap protection requires ENABLE_LOGGING_AND_PROFILING as well.
 //
@@ skipping 29 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