On Mon, Oct 15, 2012 at 9:35 AM, Gabor Rapcsanyi <rga...@inf.u-szeged.hu>wrote:
> On 10/12/2012 11:23 AM, Tom Hudson wrote: > > Do you have particular bottleneck functions that you have reason to > believe would benefit from ARM SIMD optimizations? Under what > workloads, and how much benefit? > > We've see a few ridiculously expensive transform functions in WebKit > that my colleagues in Chapel Hill might be able to recall, but usually > it's the rendering engines that are hot, not WebKit itself. > > Yes, you're right that the rendering engine is usually the basic > bottleneck, > but why shouldn't we optimize WebKit where it is possible. > For example the function what you asking is > TransformationMatrix::multiply(). > I made a test which could be speed up with optimizing this matrix > multiplication. > I uploaded here: https://bugs.webkit.org/show_bug.cgi?id=98913 > You are suggesting a massive change to WebKit based on an hypothetical universe in which a certain function is important. The problem is the same claim can be done for about any function of WebKit. You can handcraft a microbenchmark exercising a slow function and redesign everything to make that particular function fast. Does this add a lot of value to the project? No so much. As much as I am in favor of increasing the use of SIMD, especially on ARM, I am really not a fan of the idea of switching to float on such weak premises. Benjamin
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