Fwd: Would you send me your hard float experiment results you presented in Budapest?
jserv at 0xlab.org
Sat Sep 3 13:18:53 UTC 2011
2011/9/3 Christian Robottom Reis <kiko at linaro.org>:
> On Tue, Aug 30, 2011 at 11:24:59AM -0500, Zach Pfeffer wrote:
>> I'd like you to meet Jim who did the initial hardfloat work. This
>> email contains the results that Jim produced.
> Hmm, but the email seems to not actually contain a hard-float run. Or am
> I misreading what he means by Fixed vs VFP?
In fact, the presentation was incomplete. That is exactly the reason
why I didn't want to make it public.
The original plans were as following:
- Analyze skia and webkit for soft/hard-fp
- Select fixed-point, soft-vfp, and hard-fp implementations in skia
and then check the benchmark results.
However, I didn't make all benchmark results ready when I built with
hard-fp. I didn't know why and stopped the study due to personal
reasons. (sorry for being absent)
>> I believe that the conclusion was that skia and webkit may benefit,
>> but that such benefits would impose an undue burden on Android's
>> distribution model which tries to create libs that can run on as many
>> architectures as possible.
> You may be confusing things here. Hard-float is a pure software ABI
> change, and any platform which supports VFP can use it if you build it
> that way. However, since it is an ABI change it requires that hard-float
> libraries be available.
Yes, since ABI has to be changed, we have to confirm the modifications
against existing components:
- dalvik fast-interpreter and jitter
- v8 compiler/evaluator
- android software OpenGL|ES renderer
Again, please don't be too serious about my incomplete materials.
I didn't have enough time to analyze that time.
> What /would/ stop code from running on certain platforms is using
> NEON (it would exclude the Tegra2 and some existing Marvell v7s). But
> that doesn't seem to be in question here.
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