[Webkit-unassigned] [Bug 98694] [Performance] Speed-up DOM tree traversal on ARM platforms

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=98694





--- Comment #17 from Benjamin Poulain <benjamin at webkit.org>  2012-10-11 17:11:28 PST ---
>     - Not making NULL check for PLD addresse seems to have very negative impact on both X86 and ARM based architectures.

This is very surprising for ARM. In the design document, it says PLD has been designed explicitly with the branch issue in mind. Loading an invalid address has no impact, while the branch will cost cycles on misspredictions.

Have you only tested on Krait or did you get to try on a "regular" implementation of ARMv7? Because krait is more the exception than the norm.

Have you tried having Node::updatePrefetchTarget() implemented but being an NOOP? Because Node::updatePrefetchTarget() influence the cache so you are not measuring the PLD alone.

Very nice work in any case.
I think we may have to tweak the stride size by ARM implementation.

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