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

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

Raspberry Pi 1 B+ (700MHz single-core ARMv6)
--profile_period=1000  DeltaBlue(RunTime): 231748.1111111111 us.
--profile_period=10000 DeltaBlue(RunTime): 117826.64705882352 us.
--profile_period=20000 DeltaBlue(RunTime): 111494.05555555555 us.
--profile_period=50000 DeltaBlue(RunTime): 101028.45000000001 us.
--profile=false        DeltaBlue(RunTime): 100488.70000000001 us.

Raspberry Pi 2 B (900MHz quad-core ARMv7)
--profile_period=1000  DeltaBlue(RunTime): 19612.676470588238 us.
--profile_period=10000 DeltaBlue(RunTime): 18774.51401869159 us.
--profile_period=20000 DeltaBlue(RunTime): 18611.314814814818 us.
--profile_period=50000 DeltaBlue(RunTime): 18940.10377358491 us.
--profile=false        DeltaBlue(RunTime): 18242.463636363635 us.

R=johnmccutchan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45432

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

rmacnak@google.com changed reviewers:
+ johnmccutchan@google.com

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

https://chromiumcodereview.appspot.com/1108123002/diff/1/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (left):

https://chromiumcodereview.appspot.com/1108123002/diff/1/runtime/vm/profiler....
runtime/vm/profiler.cc:28: #if defined(TARGET_OS_ANDROID) ||
defined(HOST_ARCH_ARM64)
Why host?

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

Thanks! LGTM, but, we should watch the bots for fall out.

https://chromiumcodereview.appspot.com/1108123002/diff/1/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (left):

https://chromiumcodereview.appspot.com/1108123002/diff/1/runtime/vm/profiler....
runtime/vm/profiler.cc:28: #if defined(TARGET_OS_ANDROID) ||
defined(HOST_ARCH_ARM64)
On 2015/04/27 21:06:18, rmacnak wrote:
> Why host?

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

[rmacnak, 2015-04-27 21:45:55]

Committed patchset #1 (id:1) manually as 45432 (presubmit successful).