Adds AVX detection to CPU and records a histogram of Intel uArch Support

chrome/browser/chrome_browser_main.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chrome_browser_main.h"
 
 #if defined(TOOLKIT_GTK)
 #include <gtk/gtk.h>
 #endif
 
 #include <string>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/cpu.h"
 #include "base/debug/trace_event.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/prefs/json_pref_store.h"
 #include "base/process_info.h"
 #include "base/process_util.h"
 #include "base/run_loop.h"
@@ skipping 937 matching lines @@
 }
 
 int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
   // Android updates the metrics service dynamically depending on whether the
   // application is in the foreground or not. Do not start here.
 #if !defined(OS_ANDROID)
   // Now that the file thread has been started, start recording.
   StartMetricsRecording();
 #endif
 
+#if defined(ARCH_CPU_X86_FAMILY)

[apatrick_chromium, 2013/01/25 19:06:30]

Consider extracting this code to a function defined in another file and calling
it from here.

+  base::CPU cpu;
+  int arch = 0;
+  if (cpu.has_sse()) arch = 1;

[apatrick_chromium, 2013/01/25 19:06:30]

style nit: Drop body to its own line.

Also can you use an enum, make the last field be the number of fields (currently
8) and comment the enum with a warning that it must not be reordered and that it
must be kept in sync with histograms.xml?

+  if (cpu.has_sse2()) arch = 2;
+  if (cpu.has_sse3()) arch = 3;
+  if (cpu.has_ssse3()) arch = 4;
+  if (cpu.has_sse41()) arch = 5;
+  if (cpu.has_sse42()) arch = 6;
+  if (cpu.has_avx()) arch = 7;
+  UMA_HISTOGRAM_ENUMERATION("Platform.IntelMaxuArchSupport", arch, 8);

[apatrick_chromium, 2013/01/25 19:06:30]

A search for "Intel Maxu Arch" yields nothing. What is "Maxu"? Is it "Max"?

[whunt, 2013/01/30 23:53:11]

uArch is a very common (at least at Intel...) abbreviation for micro
architecture (following the m, u <- greek mu, p convention for mili, micro,
pico)  It doen't really work if you capitalize it.  I'll make Micro more
explicit.

+#endif // defined(ARCH_CPU_X86_FAMILY)
+
   // Create watchdog thread after creating all other threads because it will
   // watch the other threads and they must be running.
   browser_process_->watchdog_thread();
 
   // Do any initializating in the browser process that requires all threads
   // running.
   browser_process_->PreMainMessageLoopRun();
 
   // Record last shutdown time into a histogram.
   browser_shutdown::ReadLastShutdownInfo();
@@ skipping 659 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead_";
     uma_name += pre_read_percentage;
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }