Firefox OS/Performance/Investigating Alerts

When you get an email from fxos-perf-alerts@mozilla.com, there is a good chance it is an automated email.

We have two types of automated alerts:

• Ingestion Alerts (we were expecting data and never received it)
• Regression Alerts (the values of the reported data have changed)

Regression Alerts

A regression alert has a Title in this format

'[ALERT][B2G] <testname> regressed by <-x.x> in <suite>'

example

'[ALERT][B2G] email_memory regressed by -3.6 in vsize, vsize'

The first part of the Alert is the score:

The score can map directly to the confidence of the alert sustaining over time. The range is from 2-4 where 4 is .9999% sure. In the above example, we have a score of 3.32 which is .99932% confident this is a sustained regression.

Summary

The next section gives you direct links to the code that built B2G used for this test.

The gaia revision is a link to github that shows the specific changes to gaia.

The gecko revision is a link to github showing the current revision of gecko that we are using. bug 1010384 tracks getting these links to work.

Detailed Regressions

The last section of the alert is the details of the regression. For the given build, there could be many regressions found, we will list all of them in this section.

We outline which device model is used. The example here is Tarako, Other values are Hamachi as well.

After the device we mention what suite showed a regression. In this example we have 'vsize' as the suite:

The suite can be:

• vsize
• sms
• browser
• communication/contacts
• video
• fps
• email
• music
• gallery
• and a few others

• • bug 1010391 - document suite names and what each suite does

Next is the testname that was run inside of the suite. In this example we have 'email_memory':

Other testnames can be:

• email_memory
• communications/dialer_memory
• cold_load_time
• startup/startup_path_done
• etc.

• • bug 1010396 - document test names in detail

The next section is the Datazilla links, these are mostly self explanatory and for more information on what the view in Datazilla means check out Bisecting_Regressions:

After the links to Datazilla, we show a link to a diff of the Gaia repository (all changes from the previous test run to the current one):

The next field is the date. This is the date that the results were posted to Datazilla. Not the date we did the build or started the test run. Not the date that we detected the regression. Since the alerting system waits for future data, this date will be a few hours older than the email:

The last section of the details is the raw numbers for Before, After, and Diff:

* Before - the MEAN value of the previous 10 data points you see on the graph
* After - the MEAN value of the current data point + 9 future ones which are seen on the graph
* Diff - After - Before