Add DeadlineOverrun step to the RendererSchedulerIdlePeriod trace event.

Add DeadlineOverrun step to the RendererSchedulerIdlePeriod trace event.

Adds a deadline overrun step to the RendererSchedulerIdlePeriod trace event
to make it obvious when an idle period lasts longer than its deadline.

Also adds a TRACE_EVENT_ASYNC_STEP_INTO_WITH_TIMESTAMP0 which is required
to add the step at the appropriate time.

BUG=455713
Committed: https://crrev.com/a38b72b5f1ec147bb961e9045ca0c165f428d5e4
Cr-Commit-Position: refs/heads/master@{#315042}

Committed: https://crrev.com/75c2b017bd1ab668d7f20fde6af6f5506a842c02
Cr-Commit-Position: refs/heads/master@{#316080}

[rmcilroy, 2015-02-06 11:41:16]

rmcilroy@chromium.org changed reviewers:
+ nduca@chromium.org, skyostil@chromium.org

[rmcilroy, 2015-02-06 11:41:16]

Nat: please review the change in base/trace_event
Sami: please review the change in renderer/scheduler

PTAL, thanks!

[dsinclair, 2015-02-06 14:43:21]

dsinclair@chromium.org changed reviewers:
+ dsinclair@chromium.org

[dsinclair, 2015-02-06 14:43:21]

base/trace_event lgtm.

[Sami, 2015-02-06 14:52:02]

Neat, lgtm.

[rmcilroy, 2015-02-06 14:58:30]

The CQ bit was checked by rmcilroy@chromium.org

[picksi, 2015-02-06 14:59:07]

Do we track how long the idle period was? I would guess that overruns would
become more frequent as the idle periods got smaller - we may be able to
estimate a fudge-factor (or lower limit) to reduce the number of idle tasks that
attempt to run when it is unwise to do so.

[commit-bot: I haz the power, 2015-02-06 14:59:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/908473002/1

[rmcilroy, 2015-02-06 15:14:29]

On 2015/02/06 14:59:07, picksi wrote:
> Do we track how long the idle period was? I would guess that overruns would
> become more frequent as the idle periods got smaller - we may be able to
> estimate a fudge-factor (or lower limit) to reduce the number of idle tasks
that
> attempt to run when it is unwise to do so.

Yes we track this (the TRACE_EVENT_ASYNC_BEGIN/END0("renderer.scheduler",
"RendererSchedulerIdlePeriod" track the overall length of the idle times).  

Good idea on the fudge-factor.  I think that currently tasks are being fairly
conservative currently (so they just won't run at all for small deadlines), so
we might not see this in the overrun data, but it doesn't really make any sense
for us to start an idle period if nothing would use it.  I'll keep this in mind
to do.

[rmcilroy, 2015-02-06 15:17:33]

On 2015/02/06 15:14:29, rmcilroy wrote:
> On 2015/02/06 14:59:07, picksi wrote:
> > Do we track how long the idle period was? I would guess that overruns would
> > become more frequent as the idle periods got smaller - we may be able to
> > estimate a fudge-factor (or lower limit) to reduce the number of idle tasks
> that
> > attempt to run when it is unwise to do so.
> 
> Yes we track this (the TRACE_EVENT_ASYNC_BEGIN/END0("renderer.scheduler",
> "RendererSchedulerIdlePeriod" track the overall length of the idle times).  
> 
> Good idea on the fudge-factor.  I think that currently tasks are being fairly
> conservative currently (so they just won't run at all for small deadlines), so
> we might not see this in the overrun data, but it doesn't really make any
sense
> for us to start an idle period if nothing would use it.  I'll keep this in
mind
> to do.

Created crbug.com/456124 to remind me to do this :).

[commit-bot: I haz the power, 2015-02-06 16:06:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-06 16:06:53]

Patchset 1 (id:??) landed as
https://crrev.com/a38b72b5f1ec147bb961e9045ca0c165f428d5e4
Cr-Commit-Position: refs/heads/master@{#315042}

[gab, 2015-02-12 16:14:03]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/916223004/ by gab@chromium.org.

The reason for reverting is: http://crbug.com/456940#c17.

[rmcilroy, 2015-02-12 18:05:51]

New patchsets have been uploaded after l-g-t-m from
dsinclair@chromium.org,skyostil@chromium.org

[rmcilroy, 2015-02-12 21:41:37]

On 2015/02/12 16:14:03, gab wrote:
> A revert of this CL (patchset #1 id:1) has been created in
> https://codereview.chromium.org/916223004/ by mailto:gab@chromium.org.
> 
> The reason for reverting is: http://crbug.com/456940#c17.

Relanding with fix in patch-set #2.

[rmcilroy, 2015-02-12 21:41:40]

The CQ bit was checked by rmcilroy@chromium.org

[commit-bot: I haz the power, 2015-02-12 21:42:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/908473002/20001

[commit-bot: I haz the power, 2015-02-12 23:27:49]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-12 23:28:44]

Patchset 2 (id:??) landed as
https://crrev.com/75c2b017bd1ab668d7f20fde6af6f5506a842c02
Cr-Commit-Position: refs/heads/master@{#316080}