I think this hUMA/HSA is a value proposition and not meant for high-end graphics or GPGPU, which can easily stream through GBs of data very quickly (high end cards have > 4 GB on card). Even Haswell strikes me as a value product; everything great until your problem doesn't fit into your cache.
The transparent memory hierarchy is still quite expensive, and there are lots of performance benefits, at least at the high end, to managing it yourself.
>I think this hUMA/HSA is a value proposition and not meant for high-end graphics or GPGPU, which can easily stream through GBs of data very quickly (high end cards have > 4 GB on card).
I think the use of it in gaming consoles goes against that a bit. I also don't see why you're combining the architecture with the specific hardware. You're thinking x86 CPU with an embedded-class GPU in it. What happens if they build a high end GPU with a CPU in it? Nothing stops them from putting 4GB of DRAM on the same package as that like they do with GPUs (or did historically with SRAM on Slot-based CPUs). You can certainly imagine a market for both, the later would just be the expensive / high end model of the former.
And if you really, actually need a dedicated GPU for some highly specialized workload, I imagine you'll still be able to buy one. But now you're talking about the market where people currently put four GPUs into one box, which is not exactly mass market.
There are a lot of performance benefits to managing the memory hierarchy yourself. But I think that the demise of the Cell demonstrated that not enough people are willing to do it to justify it as architectural decision.
I was talking about for a single chip. There was a lot of interest in Cell in the HPC market, but it also died.
For applications that can tolerate the latency, offloading computation to the GPUs is such a multiplier in performance that they have to put up with manually managing the hierarchy - but even there, it's a rather coarse memory management.
The transparent memory hierarchy is still quite expensive, and there are lots of performance benefits, at least at the high end, to managing it yourself.