1141915 - Graph MSE video mean-time-between-rebuffering (MTBR)

Status: RESOLVED FIXED

(Data Platform and Tools :: General, defect)

Description

[cajbir (:cajbir)]

This is spun from bug 1127646 comment 13:

"The telemetry.mozilla.org infra can't show you that because it's a relation between two separate datapoints. But with a histogram of pauses and a counter/histogram of total time, the realtime dashboard can graph that over time. File a dashboard bug and it'll be quick!"

Given a telemetry exponential histogram for a time, and a telemetry count, enable combining these to show time/count over time.

This is used for MSE where we want to show mean time between rebuffering given a total play time and a buffering count.

Comment 1

[Benjamin Smedberg]

I'm not sure we want to deal with doing this generically, but it should be easy enough to do for this specific case.

Comment 2

[Benjamin Smedberg]

http://bsmedberg.github.io/mozilla-video-mtbr-dashboard/
https://github.com/bsmedberg/mozilla-video-mtbr-dashboard

Comment 3

[Roberto Agostino Vitillo (:rvitillo)]

cajbir, the sum of bin counts of VIDEO_MSE_PLAY_TIME_MS equals VIDEO_MSE_BUFFERING_COUNT, i.e. for each buffering event there is an associated play time. Benjamin mentioned that we shouldn't get a BUFFERING_COUNT for the initial load of the video, only for "internal" buffering, and that PLAY_TIME should only be reported once per video.

Comment 4

[cajbir (:cajbir)]

The data is only recorded once per video isn't it? The telemetry recording is done when the video is unloaded.

Comment 5

[Roberto Agostino Vitillo (:rvitillo)]

Chris, below is a typical submission. As you can see the sum of bucket counts for VIDEO_MSE_PLAY_TIME_MS equals the value stored in VIDEO_MSE_BUFFERING_COUNT. The problem is in [0], you are passing in a count to Accumulate but as documented in [1], a count histogram "only stores a single value and it can only be incremented by one with each add/accumulate call".

[0] https://dxr.mozilla.org/mozilla-central/source/dom/html/HTMLMediaElement.cpp#2595
[1] https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Adding_a_new_Telemetry_probe

VIDEO_MSE_PLAY_TIME_MS histogram:
0         4
395       1
621       1
722       1
840       1
977       1
1136      1
2415      1
3798      1
5974      1
6947      1
8079      1
19984     1
23240     1
36552     1
57488     1
66855     3
90416     1
142203    1
165373    2
223653    1
260093    1
302471    1
351754    1

VIDEO_MSE_BUFFERING_COUNT
value: 30

Comment 6

[cajbir (:cajbir)]

Thanks for that breakdown, I've raised bug 1145004 to address it.