Enable profiler by default on Android, and reduce profiler sampling rate for An droid, ARM and MIPS.

runtime/vm/profiler.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/address_sanitizer.h"
 #include "platform/memory_sanitizer.h"
 #include "platform/utils.h"
 
 #include "vm/allocation.h"
 #include "vm/atomic.h"
 #include "vm/code_patcher.h"
 #include "vm/instructions.h"
 #include "vm/isolate.h"
 #include "vm/json_stream.h"
 #include "vm/lockers.h"
 #include "vm/native_symbol.h"
 #include "vm/object.h"
 #include "vm/os.h"
 #include "vm/profiler.h"
 #include "vm/reusable_handles.h"
 #include "vm/signal_handler.h"
 #include "vm/simulator.h"
 #include "vm/stack_frame.h"
 
 namespace dart {
 
-
-#if defined(TARGET_OS_ANDROID) || defined(HOST_ARCH_ARM64)

[rmacnak, 2015/04/27 21:06:18]

Why host?

[Cutch, 2015/04/27 21:19:52]

I think Zach had disabled this early in development of ARM64.

-  DEFINE_FLAG(bool, profile, false, "Enable Sampling Profiler");
+DEFINE_FLAG(bool, profile, true, "Enable Sampling Profiler");
+DEFINE_FLAG(bool, trace_profiled_isolates, false, "Trace profiled isolates.");
+#if defined(TARGET_OS_ANDROID) || defined(TARGET_ARCH_ARM64) ||                \
+    defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_MIPS)
+  DEFINE_FLAG(int, profile_period, 10000,
+              "Time between profiler samples in microseconds. Minimum 50.");
 #else
-  DEFINE_FLAG(bool, profile, true, "Enable Sampling Profiler");
+  DEFINE_FLAG(int, profile_period, 1000,
+              "Time between profiler samples in microseconds. Minimum 50.");
 #endif
-DEFINE_FLAG(bool, trace_profiled_isolates, false, "Trace profiled isolates.");
-DEFINE_FLAG(int, profile_period, 1000,
-            "Time between profiler samples in microseconds. Minimum 50.");
 DEFINE_FLAG(int, profile_depth, 8,
             "Maximum number stack frames walked. Minimum 1. Maximum 255.");
 #if defined(PROFILE_NATIVE_CODE) || defined(USING_SIMULATOR)
 DEFINE_FLAG(bool, profile_vm, true,
             "Always collect native stack traces.");
 #else
 DEFINE_FLAG(bool, profile_vm, false,
             "Always collect native stack traces.");
 #endif
 
@@ skipping 1026 matching lines @@
                                         state.fp,
                                         sp);
     stackWalker.walk();
   } else {
     sample->set_vm_tag(VMTag::kEmbedderTagId);
     sample->SetAt(0, state.pc);
   }
 }
 
 }  // namespace dart