Bug 175712 – REGRESSION(r220479): ~8% regression on Speedometer 2 Inferno test

• Component: New Bugs
• Status: NEW

[Ryosuke Niwa]

We have a regression on Speedometer 2 (beta)'s Inferno test case:
https://perf.webkit.org/v3/#/charts?since=1500698643580&zoom=(1502150451716.6733-1502403902967.6519)&paneList=((18-977-(1502293749323.2402-1502346683886.86)-null-(5-2.5-500))-(18-896-28434716)-(18-946-28436480))&repository=1

I've made a reduced test case that just runs this test case and the results are follows:

r220473:
66.3 ± 0.72
65.1 ± 0.66

r220476
64.6 ± 0.89
66.58 ± 0.64
65.6 ± 0.78

r220479
62.63 ± 0.51
62.4 ± 0.72
62.2 ± 0.77

r220494:
62.8 ± 1.1
62.69 ± 0.57
62.6 ± 0.89

[Ryosuke Niwa]

Created attachment 318475 [details]
Patch to only enable Inferno subtest

Apply this patch and "Disable Local File Restrictions" in Develop menu to run the test.

[Chris Dumez]

I think it is unlikely to be Sam's https://trac.webkit.org/changeset/220477/webkit. If anything, Sam's patch drops an "if" branch in many cases.

Zalan / Dave should probably take a second look at https://trac.webkit.org/changeset/220479/webkit.

[Ryosuke Niwa]

I've manually built & confirmed the regression comes from r220479:

r220478
67.2 ± 0.82
67.7 ± 0.69
67.9 ± 0.68
66.8 ± 0.92

r220479
63.7 ± 1.2
63.3 ± 0.82
65.53 ± 0.64
64.18 ± 0.55

[Ryosuke Niwa]

Created attachment 318539 [details]
Reduced test case