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Game now forces use of ONLY the discrete GPU
it basically disables my Iris Pro integrated GPU for dual use with the discrete GPU on VO.
iMac 21.5in 2013, Iris pro, NVIDIA 750M
iMac 21.5in 2013, Iris pro, NVIDIA 750M
You can't have it both ways.
What problem is using the discrete GPU causing?
What problem is using the discrete GPU causing?
Well the iMac I use uses both GPU for graphics processing. Unlike the older models it doesn't switch between them, but uses both.
The problem is that since its forcing all VO graphics work to be done by the discrete GPU, at some point in the future when VO becomes more graphics intensive, it'll cause problems.
I made this happen by simply running two instances of Vendetta, and my integrated graphics card did nothing.
The problem is that since its forcing all VO graphics work to be done by the discrete GPU, at some point in the future when VO becomes more graphics intensive, it'll cause problems.
I made this happen by simply running two instances of Vendetta, and my integrated graphics card did nothing.
I could be wrong, but I imagine the use of both is simply to offload some of the work from the discrete GPU so you aren't using a sledge hammer for something the size of a nail. This would be beneficial for a mobile device like a laptop for the sake of battery life. Coupled with the fact that not all macs have both GPUs, you're probably better of sticking with the discrete.
A Mac OS X app can only use one as its main GPU It could theoretically use the other one to do work like generating shadow maps or some other real-time texture generation (or GPGPU calculations) but that would need to be explicitly coded up to do and isn't a priority right now because of the limited number of devices with multiple GPUs.
http://i568.photobucket.com/albums/ss128/eprosis/Screen%20Shot%202015-04-24%20at%201.05.50%20am_zpsei65elep.png
Can zoom in there. But basically no VRAM on the integrated Iris Pro is being used by VO when it used to before the update.
Ray's point is that there is no performance downside to this, nor will there ever be.
The Macbook, like all dual-GPU laptops, offers discrete vs integrated as a power-saving option. Yes, you might have seen resident ram loaded on the integrated GPU, so the laptop could auto-switch if the graphical load were lower, and perhaps you would save some battery life for a little while.
But, even as Apple explicitly says, there are a lot of products that require the discrete GPU (in their example, Aperture, an Apple product).
The idea that the machine is really using "both" GPUs, at the same time, for a single application, is incorrect. As Ray says, that would require some highly specialized work, as they do not have a unified driver architecture. The closest you would get to "both" is that the OS might be able to use the integrated for OS-desktop rendering, and the windowed-game would use discrete. But this would still be a battery-saving technique, and not a performance advantage.
Yes, there are lots of high-end desktops with multiple GPUs that are faster for it, but that is not the same situation at all. They all share the same driver architecture, they're all the same speed/type, and are basically used as one giant GPU with a super fast bus connecting them. That is not at all the case with an Intel integrated GPU and a discrete GPU.
So, the only argument to be made against our using the discrete GPU exclusively, is that you will have reduced battery performance.
But, considering the reason why we did this was due to complaints that (in some cases) it wasn't using the discrete GPU at all, and the performance was degraded.. this seems like a reasonable sacrifice. If you're playing VO, you're probably going to want to be on the discrete GPU. And probably plugged in anyway.
The Macbook, like all dual-GPU laptops, offers discrete vs integrated as a power-saving option. Yes, you might have seen resident ram loaded on the integrated GPU, so the laptop could auto-switch if the graphical load were lower, and perhaps you would save some battery life for a little while.
But, even as Apple explicitly says, there are a lot of products that require the discrete GPU (in their example, Aperture, an Apple product).
The idea that the machine is really using "both" GPUs, at the same time, for a single application, is incorrect. As Ray says, that would require some highly specialized work, as they do not have a unified driver architecture. The closest you would get to "both" is that the OS might be able to use the integrated for OS-desktop rendering, and the windowed-game would use discrete. But this would still be a battery-saving technique, and not a performance advantage.
Yes, there are lots of high-end desktops with multiple GPUs that are faster for it, but that is not the same situation at all. They all share the same driver architecture, they're all the same speed/type, and are basically used as one giant GPU with a super fast bus connecting them. That is not at all the case with an Intel integrated GPU and a discrete GPU.
So, the only argument to be made against our using the discrete GPU exclusively, is that you will have reduced battery performance.
But, considering the reason why we did this was due to complaints that (in some cases) it wasn't using the discrete GPU at all, and the performance was degraded.. this seems like a reasonable sacrifice. If you're playing VO, you're probably going to want to be on the discrete GPU. And probably plugged in anyway.