Upping the priority since this is blocking us understanding system health regressions.

Dave, Roberto, can you take a look at this today?

Dave, these are some of the issues I mentioned yesterday during speed-infra meeting.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/build.git/+/6a0ae9a267cf531c5730e35900d3ec7cd1f4f20e

commit 6a0ae9a267cf531c5730e35900d3ec7cd1f4f20e
Author: dtu <dtu@chromium.org>
Date: Tue Aug 30 18:14:50 2016

Increase timeout for determining initial confidence from 2 hours to 20 hours.

Some benchmarks take up to 40 minutes to run. 2 hours only gets you 4
iterations. That's not enough to establish confidence for many regressions. If
you want to get up to 15 iterations of both the first and last commits, that's
20 hours. A build times out after 24 hours, so 20 seems like a good number with
some headroom.

Unfortunately, if it takes that long to establish confidence, the bisect run
will probably time out after 24 hours, anyway. You could argue that we're
wasting bisect resources doing this, but having a timeout would be clearer to
the user than having a no-confidence result.

Long term fix would be to implement --story-filter for benchmarks that we can
divide up, to reduce the run time:
https://github.com/catapult-project/catapult/issues/1811
Also swarming will remove that 24-hour timeout restriction, I believe.

BUG= 640509 

Review-Url: https://codereview.chromium.org/2273173002

[modify] https://crrev.com/6a0ae9a267cf531c5730e35900d3ec7cd1f4f20e/scripts/slave/recipe_modules/auto_bisect/bisector.py

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/chrome/tools/build_limited/scripts/slave/+/caecd47f1df23a71d9722df900465341ba0f2ddf

commit caecd47f1df23a71d9722df900465341ba0f2ddf
Author: recipe-roller <recipe-roller@chromium.org>
Date: Tue Aug 30 18:34:53 2016

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f5c0fd8043162d7fe1a5dcbaad349ce56245fbed

commit f5c0fd8043162d7fe1a5dcbaad349ce56245fbed
Author: recipe-roller <recipe-roller@chromium.org>
Date: Tue Aug 30 20:06:16 2016

Roll recipe dependencies (trivial).

This is an automated CL created by the recipe roller. This CL rolls recipe
changes from upstream projects (e.g. depot_tools) into downstream projects
(e.g. tools/build).

More info is at https://goo.gl/zkKdpD. Use https://goo.gl/noib3a to file a bug
(or complain)

build:
  https://crrev.com/6a0ae9a267cf531c5730e35900d3ec7cd1f4f20e Increase timeout for determining initial confidence from 2 hours to 20 hours. (dtu@chromium.org)
  https://crrev.com/b558a1d492b1e80a75c1fe4d76a39606e872a305 Make Nexus5X bisect bot  use 64 bit binaries. (prasadv@google.com)
  https://crrev.com/c55d5672010c188fec90d8aa2b2ccc83be6f5c07 Add configs for android webview Nexus 6 bisect bot. (mikecase@chromium.org)

TBR=martiniss@chromium.org,phajdan.jr@chromium.org
BUG=640154, 640509 

Recipe-Tryjob-Bypass-Reason: Autoroller
Bugdroid-Send-Email: False
Review-Url: https://codereview.chromium.org/2298463002
Cr-Commit-Position: refs/heads/master@{#415404}

[modify] https://crrev.com/f5c0fd8043162d7fe1a5dcbaad349ce56245fbed/infra/config/recipes.cfg

Is there anything else we might want to do about this?

I haven't seen any recent examples of this happening.

+Simon, who's been working bisect lately

This is old and we're starting to file about repro on individual benchmarks now.