Metal and rMBP's with dGPU's

Discussion in 'OS X El Capitan (10.11)' started by Blue Sun, Oct 26, 2015.

  1. Blue Sun macrumors 6502a

    Feb 11, 2009
    Metal is not supported on rMBP's with dGPU's when UI animations are concerned, even when the iGPU is engaged. Will Apple ever implement Metal on these systems when using the iGPU or dGPU for UI animations? Has there been any talk of this?

    If Metal is not implemented on these machines, then iGPU-only Macs (i.e the cheaper, less powerful Macs) will always have the upper hand at UI fluidity (Mission Control, resizing windows etc). This is pretty strange to me, and a little unfair if you think about it.

    In my experiences, El Capitan isn't much smoother than Yosemite, which may be due to the lack of Metal. FWIW, I'm running the late 2013 15" rMBP with Iris Pro and GT 750m.
  2. leman macrumors G3

    Oct 14, 2008
    I am sure they will eventually. It makes sense to start small. Besides, the iGPU is used for UI acceleration mot of the time anyway. And switching between iGPU and dGPU on the flight is tricky, so they have probably felt that their implementation of it is too immature right now to be released to the public.

    The primary benefit of Metal for UI acceleration is power efficiency, not performance per se. Performance increases in Metal come from more efficient batching, i.e. the CPU is able to offload the work to the GPU more quickly which allows one to optimal utilise the computational resources. But this is not an issue when drawing the UI in the first place. So while there might be some small performance increases, its nothing you are likely to register.

    Besides, the(modern) iGPU is (at least in theory) better suited for doing UI composition than the dGPU. Its decisive benefit is that one does not need to synchronise system RAM and graphical RAM. Modern iGPUs have more then enough bandwidth and texturing power to fill a retina screen hundreds and hundreds of times per second which is absolutely sufficient for UI composition.

    My experience is similar, simply because Yosemite was already pretty damn smooth on my computer ;) El Capitan does bring some serious improvements in a number of areas (e.g. Mission Control), but this is because they have reimplemented the base algorithm and not because of Metal.

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