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Why did lastVisualChange and SpeedIndexes3G went up for mobile/desktop.
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Description

The LastVisualChange for Barrack Obama on desktop increased (for desktop it doubled) on August 31/September 1st. For 3G connection lastVisualChange jumped from 6s to ~7s and for the desktop graph jumped from ~1.6s to ~3.2s
Also, SpeedIndexes3G increased, both for Barrack Obama and Facebook articles.
There was a small jump for JS shipped to the browser (4kb more on September 1st) - this matches the change in SpeedIndexes3G graph, but the Last Visual Change graph started to raise day before (on August 31).

Graphs: https://grafana.wikimedia.org/dashboard/db/mobile-2g?orgId=1



This happened on Friday/Saturday, most probably it's not related to the deployment (maybe because of cache we didn't see any spikes during deployment windows). Any way we can work out what caused this?

Event Timeline

pmiazga created this task.Sep 3 2018, 5:46 PM
Restricted Application added a subscriber: Aklapper. · View Herald TranscriptSep 3 2018, 5:46 PM
Krinkle added a subscriber: Krinkle.Sep 3 2018, 6:18 PM

There have been a number of metric changes we're currently looking into. This particular one I haven't seen yet, but perhaps you can take a look at wpt.wmftest.org and compare the runs represented by those plot points?

Pcoombe added a subscriber: Pcoombe.Sep 3 2018, 6:34 PM

Could it be related to CentralNotice banners? The US Wiki Loves Monuments campaign was turned on at 04:16 UTC on September 1st, which seems to coincide with the time that these metrics jumped.

Peter added a subscriber: Peter.Sep 3 2018, 7:23 PM

@Pcoombe you are right, the Wiki loves monument campaign affects Speed Index, Perceptual Speed Index and last visual change and time spent rendering. It's on both desktop and mobile. I've had a look this weekend, this is the desktop diff:

In the performance team we have the alerts that we act on that fired. We can easily add more people to the alerts but I want to add documentation how to act on it (=how to understand what's going on). Let me start with that this week and then we can have a session.

Krinkle moved this task from Inbox to Radar on the Performance-Team board.Sep 3 2018, 8:06 PM
Krinkle edited projects, added Performance-Team (Radar); removed Performance-Team.
Krinkle closed this task as Resolved.Sep 8 2018, 4:00 AM
Krinkle assigned this task to Peter.
Krinkle triaged this task as Medium priority.
Krinkle edited projects, added Performance-Team; removed Performance-Team (Radar).