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[gold patch] Add timers for each pass

Cary Coutant ccoutant@google.com
Fri Oct 14 23:51:00 GMT 2011 
Ian,

This patch adds separate timers for each of the three linker passes
(initial, middle, final). I find them useful for investigating (at a
coarse level) where --threads is helping.

It doesn't necessarily need to get checked in, but I thought I'd ask
if you think it could be generally useful.

For links out of tmpfs, it turns out that the entire speed up due to
multi-threading is in pass 3.

-cary


	* gold/gold.cc: Include timer.h.
	(queue_middle_tasks): Stamp time.
	(queue_final_tasks): Likewise.
	* gold/main.cc (main): Store timer in parameters.  Print timers
	for each pass.
	* gold/parameters.cc (Parameters::Parameters): Initialize timer_.
	(Parameters::set_timer): New function.
	(set_parameters_timer): New function.
	* gold/parameters.h (Parameters::set_timer): New function.
	(Parameters::timer): New function.
	(Parameters::timer_): New data member.
	(set_parameters_timer): New function.
	* gold/timer.cc (Timer::stamp): New function.
	(Timer::get_pass_time): New function.
	* gold/timer.h (Timer::stamp): New function.
	(Timer::get_pass_time): New function.
	(Timer::pass_times_): New data member.
-------------- next part --------------
2011-10-14  Cary Coutant  <ccoutant@google.com>

	* gold/gold.cc: Include timer.h.
	(queue_middle_tasks): Stamp time.
	(queue_final_tasks): Likewise.
	* gold/main.cc (main): Store timer in parameters.  Print timers
	for each pass.
	* gold/parameters.cc (Parameters::Parameters): Initialize timer_.
	(Parameters::set_timer): New function.
	(set_parameters_timer): New function.
	* gold/parameters.h (Parameters::set_timer): New function.
	(Parameters::timer): New function.
	(Parameters::timer_): New data member.
	(set_parameters_timer): New function.
	* gold/timer.cc (Timer::stamp): New function.
	(Timer::get_pass_time): New function.
	* gold/timer.h (Timer::stamp): New function.
	(Timer::get_pass_time): New function.
	(Timer::pass_times_): New data member.


commit dae0443e4de4facc7d9a22e36bdf6845932cfa32
Author: Cary Coutant <ccoutant@google.com>
Date:   Fri Oct 14 16:40:00 2011 -0700

    Add per-pass timers for --stats output.

diff --git a/gold/gold.cc b/gold/gold.cc
index 2700bdb..f455ec8 100644
--- a/gold/gold.cc
+++ b/gold/gold.cc
@@ -45,6 +45,7 @@
 #include "gc.h"
 #include "icf.h"
 #include "incremental.h"
+#include "timer.h"
 
 namespace gold
 {
@@ -487,6 +488,10 @@ queue_middle_tasks(const General_options& options,
 		   Workqueue* workqueue,
 		   Mapfile* mapfile)
 {
+  Timer* timer = parameters->timer();
+  if (timer != NULL)
+    timer->stamp(0);
+
   // Add any symbols named with -u options to the symbol table.
   symtab->add_undefined_symbols_from_command_line(layout);
 
@@ -786,6 +791,10 @@ queue_final_tasks(const General_options& options,
 		  Workqueue* workqueue,
 		  Output_file* of)
 {
+  Timer* timer = parameters->timer();
+  if (timer != NULL)
+    timer->stamp(1);
+
   int thread_count = options.thread_count_final();
   if (thread_count == 0)
     thread_count = std::max(2, input_objects->number_of_input_objects());
diff --git a/gold/main.cc b/gold/main.cc
index f6e7609..97a6616 100644
--- a/gold/main.cc
+++ b/gold/main.cc
@@ -165,7 +165,10 @@ main(int argc, char** argv)
 
   Timer timer;
   if (command_line.options().stats())
-    timer.start();
+    {
+      timer.start();
+      set_parameters_timer(&timer);
+    }
 
   // Store some options in the globally accessible parameters.
   set_parameters_options(&command_line.options());
@@ -252,7 +255,32 @@ main(int argc, char** argv)
 
   if (command_line.options().stats())
     {
-      Timer::TimeStats elapsed = timer.get_elapsed_time();
+      timer.stamp(2);
+      Timer::TimeStats elapsed = timer.get_pass_time(0);
+      fprintf(stderr,
+             _("%s: pass 1 run time: " \
+               "(user: %ld.%06ld sys: %ld.%06ld wall: %ld.%06ld)\n"),
+              program_name,
+              elapsed.user / 1000, (elapsed.user % 1000) * 1000,
+              elapsed.sys / 1000, (elapsed.sys % 1000) * 1000,
+              elapsed.wall / 1000, (elapsed.wall % 1000) * 1000);
+      elapsed = timer.get_pass_time(1);
+      fprintf(stderr,
+             _("%s: pass 2 run time: " \
+               "(user: %ld.%06ld sys: %ld.%06ld wall: %ld.%06ld)\n"),
+              program_name,
+              elapsed.user / 1000, (elapsed.user % 1000) * 1000,
+              elapsed.sys / 1000, (elapsed.sys % 1000) * 1000,
+              elapsed.wall / 1000, (elapsed.wall % 1000) * 1000);
+      elapsed = timer.get_pass_time(2);
+      fprintf(stderr,
+             _("%s: pass 3 run time: " \
+               "(user: %ld.%06ld sys: %ld.%06ld wall: %ld.%06ld)\n"),
+              program_name,
+              elapsed.user / 1000, (elapsed.user % 1000) * 1000,
+              elapsed.sys / 1000, (elapsed.sys % 1000) * 1000,
+              elapsed.wall / 1000, (elapsed.wall % 1000) * 1000);
+      elapsed = timer.get_elapsed_time();
       fprintf(stderr,
              _("%s: total run time: " \
                "(user: %ld.%06ld sys: %ld.%06ld wall: %ld.%06ld)\n"),
diff --git a/gold/parameters.cc b/gold/parameters.cc
index c14bd1e..7fc5730 100644
--- a/gold/parameters.cc
+++ b/gold/parameters.cc
@@ -64,7 +64,7 @@ Set_parameters_target_once set_parameters_target_once(&static_parameters);
 // Class Parameters.
 
 Parameters::Parameters()
-   : errors_(NULL), options_(NULL), target_(NULL),
+   : errors_(NULL), timer_(NULL), options_(NULL), target_(NULL),
      doing_static_link_valid_(false), doing_static_link_(false),
      debug_(0), incremental_mode_(General_options::INCREMENTAL_OFF),
      set_parameters_target_once_(&set_parameters_target_once)
@@ -79,6 +79,13 @@ Parameters::set_errors(Errors* errors)
 }
 
 void
+Parameters::set_timer(Timer* timer)
+{
+  gold_assert(this->timer_ == NULL);
+  this->timer_ = timer;
+}
+
+void
 Parameters::set_options(const General_options* options)
 {
   gold_assert(!this->options_valid());
@@ -270,6 +277,10 @@ set_parameters_errors(Errors* errors)
 { static_parameters.set_errors(errors); }
 
 void
+set_parameters_timer(Timer* timer)
+{ static_parameters.set_timer(timer); }
+
+void
 set_parameters_options(const General_options* options)
 { static_parameters.set_options(options); }
 
diff --git a/gold/parameters.h b/gold/parameters.h
index 09b0516..10de2ae 100644
--- a/gold/parameters.h
+++ b/gold/parameters.h
@@ -28,6 +28,7 @@ namespace gold
 
 class General_options;
 class Errors;
+class Timer;
 class Target;
 template<int size, bool big_endian>
 class Sized_target;
@@ -57,6 +58,9 @@ class Parameters
   set_errors(Errors* errors);
 
   void
+  set_timer(Timer* timer);
+
+  void
   set_options(const General_options* options);
 
   void
@@ -70,6 +74,11 @@ class Parameters
   errors() const
   { return this->errors_; }
 
+  // Return the timer object.
+  Timer*
+  timer() const
+  { return this->timer_; }
+
   // Whether the options are valid.  This should not normally be
   // called, but it is needed by gold_exit.
   bool
@@ -177,6 +186,7 @@ class Parameters
   friend class Set_parameters_target_once;
 
   Errors* errors_;
+  Timer* timer_;
   const General_options* options_;
   Target* target_;
   bool doing_static_link_valid_;
@@ -196,6 +206,9 @@ extern void
 set_parameters_errors(Errors* errors);
 
 extern void
+set_parameters_timer(Timer* timer);
+
+extern void
 set_parameters_options(const General_options* options);
 
 extern void
diff --git a/gold/timer.cc b/gold/timer.cc
index d9b8874..1423663 100644
--- a/gold/timer.cc
+++ b/gold/timer.cc
@@ -49,6 +49,15 @@ Timer::start()
   this->get_time(&this->start_time_);
 }
 
+// Record the time used by pass N (0 <= N <= 2).
+void
+Timer::stamp(int n)
+{
+  gold_assert(n >= 0 && n <= 2);
+  TimeStats& thispass = this->pass_times_[n];
+  this->get_time(&thispass);
+}
+
 #if HAVE_SYSCONF && defined _SC_CLK_TCK
 # define TICKS_PER_SECOND sysconf (_SC_CLK_TCK) /* POSIX 1003.1-1996 */
 #else
@@ -106,4 +115,17 @@ Timer::get_elapsed_time()
   return delta;
 }
 
+// Return the stats for pass N (0 <= N <= 2).
+Timer::TimeStats
+Timer::get_pass_time(int n)
+{
+  gold_assert(n >= 0 && n <= 2);
+  TimeStats thispass = this->pass_times_[n];
+  TimeStats& lastpass = n > 0 ? this->pass_times_[n-1] : this->start_time_;
+  thispass.wall -= lastpass.wall;
+  thispass.user -= lastpass.user;
+  thispass.sys -= lastpass.sys;
+  return thispass;
+}
+
 }
diff --git a/gold/timer.h b/gold/timer.h
index 50b55e4..339aef1 100644
--- a/gold/timer.h
+++ b/gold/timer.h
@@ -23,6 +23,8 @@
 #ifndef GOLD_TIMER_H
 #define GOLD_TIMER_H
 
+#include <vector>
+
 namespace gold
 {
 
@@ -48,10 +50,18 @@ class Timer
   TimeStats
   get_elapsed_time();
 
+  // Return the stats for pass N (0 <= N <= 2).
+  TimeStats
+  get_pass_time(int n);
+
   // Start counting the time.
   void
   start();
 
+  // Record the time used by pass N (0 <= N <= 2).
+  void
+  stamp(int n);
+
  private:
   // This class cannot be copied.
   Timer(const Timer&);
@@ -63,6 +73,9 @@ class Timer
 
   // The time of the last call to start.
   TimeStats start_time_;
+
+  // Times for each pass.
+  TimeStats pass_times_[3];
 };
 
 }
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