Bug 184499 – MotionMark gives wrong results after spectre mitigations of performance.now()

• Status: RESOLVED
• Resolution: INVALID
• Component: Tools / Tests

[Carlos Alberto Lopez Perez]

After spectre mitigations performance.now() not longer a hight resolution timer. This causes that the default settings of motionmark to give wrong results.

Motion mark supports 3 methods to measure performance as you can see here at the bottom right http://browserbench.org/MotionMark/developer.html

The default should be changed from performance.now() to one of the other methods.

[Simon Fraser (smfr)]

perf.now() and rAF timestamp should be quantized the same way, and I think Date.now() will also be.

[Carlos Alberto Lopez Perez]

(In reply to Simon Fraser (smfr) from comment #1)
> perf.now() and rAF timestamp should be quantized the same way, and I think
> Date.now() will also be.

That makes sense, actually.

I have been testing motionmark with WPE trunk and I have been getting sometimes some weird results with the default settings (like 1 points on some tests with a +-3000% percent of variance).

So, at first I thought it could be related to the spectre mitigations of performance.now() because I couldn't reproduce with the other methods of the benchmark like rAF.

But I'm not able to reproduce this with a webkit build of last trunk on Mac. So it should be something else...

I'm closing this as invalid, then.

Thanks for the comments.