1542133 - 9.45 - 12.27% build times (windows2012-64-shippable) regression on push 5851c65af0e0567d9cea916dd1d303f3b6ebe83b

Status: RESOLVED WONTFIX

(Firefox Build System :: General, defect)

Description

[Ionuț Goldan [:igoldan]]

We have detected a build metrics regression from push:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=425aab7d1e5a3deeead162cc9feb86cb4cc4da76&tochange=5851c65af0e0567d9cea916dd1d303f3b6ebe83b

As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

12% build times windows2012-64-shippable opt nightly taskcluster-c4.4xlarge 5,442.46 -> 6,110.33
9% build times windows2012-64-shippable opt nightly taskcluster-c5.4xlarge 4,556.19 -> 4,986.55

You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=20297

On the page above you can see an alert for each affected platform as well as a link to a graph showing the history of scores for this test. There is also a link to a treeherder page showing the jobs in a pushlog format.

To learn more about the regressing test(s), please see: https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Automated_Performance_Testing_and_Sheriffing/Build_Metrics

*** Please let us know your plans within 3 business days, or the offending patch(es) will be backed out! ***

Comment 1

[(Away)]

It is not surprising to see a build time increase from the additional optimizations that we enabled.

As for whether the benefits are worth the cost, I defer to Anthony.

Comment 2

[Eric Rahm [:erahm]]

FWIW this not going to affect standard developer builds unless they're doing PGO, which seems unlikely. It should also only affect "shippable" builds in automation which seems reasonable.

Comment 3

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

(In reply to David Major [:dmajor] (low availability) from comment #1)

As for whether the benefits are worth the cost, I defer to Anthony.

The increase in compilation time is expected. XLTO saves deveoper time by allowing developers to assume reasonable inlining across languages. In the past this the lack of XLTO has been worked around by generating the same code in C++ and Rust e.g. for style structs.