All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=776377

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=cd689b3bd8b52827c5b11981a88ab15934ab514c3a37fd898177381a5a054d79


Bot(s) for this bug's original alert(s):

chromium-rel-mac12

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8965293763142821264

=== BISECT JOB RESULTS ===
Perf regression found but unable to continue

Bisect was stopped because a commit couldn't be classified as either
good or bad.


Bisect Details
  Configuration: mac_10_12_perf_bisect
  Benchmark    : system_health.common_desktop
  Metric       : cpu_time_percentage_avg/load_tools/load_tools_dropbox

Revision             Result                    N
chromium@509413      0.438631 +- 0.239309      21      good
chromium@509478      0.473958 +- 0.164596      21      unknown
chromium@509543      0.479393 +- 0.216553      21      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=load.tools.dropbox system_health.common_desktop

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8965293763142821264


For feedback, file a bug with component Speed>Bisection

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8965282741348714656

=== BISECT JOB RESULTS ===
NO Perf regression found

Bisect Details
  Configuration: mac_10_12_perf_bisect
  Benchmark    : system_health.common_desktop
  Metric       : cpu_time_percentage_avg/load_tools/load_tools_dropbox

Revision             Result                    N
chromium@509413      0.440017 +- 0.316789      21      good
chromium@509543      0.415751 +- 0.266777      21      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=load.tools.dropbox system_health.common_desktop

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8965282741348714656


For feedback, file a bug with component Speed>Bisection

I don't think we have good chance of finding the culprit for a 14% change when the noise is +- 64%!

Is that right? If we characterized the noise, we could filter it out better.

I know nothing about how bisects work and I'm assuming the +- numbers in the result are x% confidence intervals, but is there a knob somewhere to increase the number of runs / revision for the purpose of tightening CIs? If not, is there a reason to not add such a thing?

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/11e5ffad040000

Running a new bisect now that pinpoint is out so we can get a better visualization of what's happening.

📍 Couldn't reproduce a difference.
https://pinpoint-dot-chromeperf.appspot.com/job/11e5ffad040000

I don't see any regression in those Pinpoint results.
The dashboard chart has returned to the original values, and the ref build results track that change pretty closely.