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Re: [Public WebGL] option for suggesting "low power" mode at context creation

One other issue needing consideration. Let's assume that the
"preferLowPowerToHighPerformance" flag is added to the
WebGLContextAttributes dictionary, and that
WebGLRenderingContext.getContextAttributes() returns the correct value
for the flag. (In other words, if the flag is set to true during
getContext, and the machine has two GPUs, and the implementation
supports low-power mode, then getContextAttributes() will return true
for the flag as well; otherwise, false.)

On dual-GPU Mac OS machines, at least, it will then be possible to get
WebGL to run on either the integrated or discrete GPU, and detect
which one is being used in JavaScript.

In order to keep implementations honest, it will be necessary to
change the WebGL conformance suite to run all of the tests twice, once
on the integrated GPU and once on the discrete GPU. Further, there are
currently many more test failures on Mac OS when running the
conformance suite on integrated GPUs than on discrete GPUs. This means
adding a low-power flag now will delay the point at which the next
snapshot of the WebGL conformance tests could be successfully passed.
There had been some hope that a new snapshot could be taken soon,
after triaging the existing test failures on top of tree.

Dean, Chris, any thoughts on this issue?


On Thu, Sep 27, 2012 at 10:22 AM, Chris Marrin <cmarrin@apple.com> wrote:
> On Sep 27, 2012, at 1:54 AM, Mark Callow <callow.mark@artspark.co.jp> wrote:
> On 12/09/27 11:27, Florian Bösch wrote:
> I don't think so. Dual GPU systems that can switch seamlessly are certainly
> somewhat of an oddity. It's certainly true that certain segments of the
> market will always aim for single GPU systems. However, if you want to
> combine very low power consumption but also powerful graphics in one system,
> dual GPU solutions will remain the solution for the forseeable future. The
> reason being that: 1) integrated graphics cannot compete performance wise
> with discrete graphics. This will always be true.
> 2) Discrete graphics cannot yet work as power effectively as simple
> integrated graphics. It is likely this will remain so for a long time due to
> this being a hard thing to do.
> 3) The need to combine both low power graphics and high power graphics in
> one system will not vanish into thin air.
> You are not giving the hardware designers much credit and nor apparently
> noticing the progress made by the latest low-power high-performance GPUs for
> mobile devices. I'm quite sure technologies for powering off unused parts of
> devices will migrate from CPUs to GPUs.
> There is no "need to combine both low power graphics and high power graphics
> in one system." There *is* a need for high-performance graphics that
> consumes low power. The current dual-GPU solution is a hack.
> No matter how good, no hardware can consistently guess your preferences.
> Turning on a low power flag might ignore the anti-aliasing flag because it
> uses a lot of power. Or might not because the GPU can do it without much
> additional battery drain. There are many other features future GPUs could
> turn on or off to sacrifice performance or quality for the sake of battery
> life. I think a flag like this gives the author the ability to make some
> very mobile friendly content.
> Regards
>     -Mark
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