Reland: Add a trace-event for each runtime-stats timer (CL 2052523002)

Reland: Add a trace-event for each runtime-stats timer (CL 2052523002)

The trace-events will have a high overhead when turned on, but they are in a disabled-by-default category.

As long as the off overhead is negligible, this CL allows us to understand the behavior of V8 rather than its performance at the moment.

The original CL was failing the TSAN builder, the variable in question was intended to be accessed quickly with no guarantee.
Switched to using an Atomic variable with no barrier read/write.

BUG=v8:5089
patch from issue 2052523002 at patchset 100001 (http://crrev.com/2052523002#ps100001)

Committed: https://crrev.com/fd7080cbefc21f2f890b5db00d4eadf163e2cbbf
Cr-Commit-Position: refs/heads/master@{#36973}

[fmeawad, 2016-06-13 19:03:40]

fmeawad@chromium.org changed reviewers:
+ cbruni@chromium.org

[fmeawad, 2016-06-13 19:03:41]

Hi cbruni,

Patch #1 has the changes for the reland.

PTAL

[Camillo Bruni, 2016-06-14 08:27:09]

lgtm

[fmeawad, 2016-06-14 14:57:44]

The CQ bit was checked by fmeawad@chromium.org

[commit-bot: I haz the power, 2016-06-14 14:57:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2063853002/20001

[commit-bot: I haz the power, 2016-06-14 15:03:23]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-14 15:05:17]

Description was changed from

==========
Reland: Add a trace-event for each runtime-stats timer (CL 2052523002)

The trace-events will have a high overhead when turned on, but they are in a
disabled-by-default category.

As long as the off overhead is negligible, this CL allows us to understand the
behavior of V8 rather than its performance at the moment.

The original CL was failing the TSAN builder, the variable in question was
intended to be accessed quickly with no guarantee.
Switched to using an Atomic variable with no barrier read/write.

BUG=v8:5089

patch from issue 2052523002 at patchset 100001
(http://crrev.com/2052523002#ps100001)
==========

to

==========
Reland: Add a trace-event for each runtime-stats timer (CL 2052523002)

The trace-events will have a high overhead when turned on, but they are in a
disabled-by-default category.

As long as the off overhead is negligible, this CL allows us to understand the
behavior of V8 rather than its performance at the moment.

The original CL was failing the TSAN builder, the variable in question was
intended to be accessed quickly with no guarantee.
Switched to using an Atomic variable with no barrier read/write.

BUG=v8:5089

patch from issue 2052523002 at patchset 100001
(http://crrev.com/2052523002#ps100001)

Committed: https://crrev.com/fd7080cbefc21f2f890b5db00d4eadf163e2cbbf
Cr-Commit-Position: refs/heads/master@{#36973}
==========

[commit-bot: I haz the power, 2016-06-14 15:05:18]

Patchset 2 (id:??) landed as
https://crrev.com/fd7080cbefc21f2f890b5db00d4eadf163e2cbbf
Cr-Commit-Position: refs/heads/master@{#36973}

[Michael Achenbach, 2016-06-15 11:43:37]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/2068143002/ by machenbach@chromium.org.

The reason for reverting is: [Sheriff] Speculative revert for
http://crbug.com/620279.