1578362 - 59.92% sccache hit rate (linux64-shippable) regression on push d2fc2720837c81d95d97eaa1539c7fe1bcbb2beb (Fri August 30 2019)

Status: RESOLVED INVALID

(Developer Infrastructure :: Lint and Formatting, defect)

Description

[Marian Raiciof [:marauder]]

We have detected a build metrics regression from push:

https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=d2fc2720837c81d95d97eaa1539c7fe1bcbb2beb

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

Regressions:

60% sccache hit rate linux64-shippable opt instrumented 0.99 -> 0.40

You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=22905

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

[Andrew Halberstadt [:ahal]]

I'm not really sure how my patch would have affected this. The only thing that I can think of that is even remotely conceivable is that it adds build/pymake to the list of third party paths in tools/rewriting/ThirdPartyPaths.txt:
https://hg.mozilla.org/integration/autoland/rev/6c0e88788302e6807ef53e4d5aa7fc9e89b44487#l4.5

Chris, do you think that could somehow affect the sccache hit rate?

If not I would strongly suspect that my change was unrelated and whatever caused the regression was something external to mozilla-central (and my push just happened to be the first unlucky one to display it).

If so, I guess we can remove build/pymake from ThirdPartyPaths.txt and instead add it to the exclude list in the license linter.

Comment 2

[Andrew Halberstadt [:ahal]]

Forgot needinfo, see above.

Comment 3

[Nathan Froyd [:froydnj]]

Judging by the graph:

https://treeherder.mozilla.org/perf.html#/graphs?series=autoland,2105108,1,2&zoom=1567211569519.084,1567511751000,0,1.0764044943820226&selected=autoland,2105108,545463,907148639,2

it's far far more likely that this is caused by:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=42ebd8a50978189a7247dc029de7d66d97e7bec9&tochange=2f873da4b36e4404b7396bf4a1403d316b8ae450

which is to be expected from a compiler change.

Comment 4

[Marian Raiciof [:marauder]]

Thanks for the updates!