Enabling RCWN causes tp6_facebook regression

RESOLVED FIXED in Firefox 57

Status

()

RESOLVED FIXED
a year ago
a year ago

People

(Reporter: michal.novotny, Assigned: michal.novotny)

Tracking

Trunk
mozilla57
Points:
---

Firefox Tracking Flags

(firefox57 fixed)

Details

(Whiteboard: [necko-active])

Attachments

(1 attachment)

(Assignee)

Description

a year ago
Comment #12 from bug 1392841:
> Before the backout, these perf regressions were noticed and also one big
> improvement:
> 
> == Change summary for alert #9249 (as of September 06 2017 12:53 UTC) ==
> 
> Regressions:
> 
>  25%  tp6_facebook summary windows7-32 pgo e10s     245.79 -> 306.62
>  22%  tp6_facebook summary windows10-64 pgo e10s    259.58 -> 315.79
>  13%  tp6_facebook summary windows10-64 opt e10s    331.31 -> 374.21
> 
> Improvements:
> 
>  27%  sessionrestore_many_windows windows10-64 pgo e10s     3,637.25 ->
> 2,643.33
> 
> For up to date results, see:
> https://treeherder.mozilla.org/perf.html#/alerts?id=9249
(Assignee)

Comment 1

a year ago
Created attachment 8906682 [details] [diff] [review]
patch

We don't know exactly what causes the regression, but the regression is gone if we don't trigger network directly from MaybeRaceCacheWithNetwork(). Triggering the network with a small delay or even just by posted event fixes the problem. 

These try pushes show the difference:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=aef04068d7d30b968fe8a23e2c1fe1ada2822193&selectedJob=130031316

https://treeherder.mozilla.org/#/jobs?repo=try&revision=b974b000b8be484bf7bc26d76762c7b2f8c4020a&selectedJob=130031233

This patch also adds network.http.rcwn.min_wait_before_racing_ms preference which can be used by users to avoid immediate racing.
Attachment #8906682 - Flags: review?(valentin.gosu)
Comment on attachment 8906682 [details] [diff] [review]
patch

Review of attachment 8906682 [details] [diff] [review]:
-----------------------------------------------------------------

Patch looks good. Adding description to the commit message would be great.
Attachment #8906682 - Flags: review?(valentin.gosu) → review+

Comment 3

a year ago
Pushed by mnovotny@mozilla.com:
https://hg.mozilla.org/integration/mozilla-inbound/rev/586734464b21
Enabling RCWN causes tp6_facebook regression, r=valentin
https://hg.mozilla.org/mozilla-central/rev/586734464b21
Status: NEW → RESOLVED
Last Resolved: a year ago
status-firefox57: affected → fixed
Resolution: --- → FIXED
Target Milestone: --- → mozilla57
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