3 ms·
>Q: In the demo of FOVEROS, the chip combined both big x86 cores built on the Core microarchitecture and the small x86 cores built on the Atom microarchitecture
by Symmetry 8y ago
>Q: In the demo of FOVEROS, the chip combined both big x86 cores built on the Core microarchitecture and the small x86 cores built on the Atom microarchitecture. Can we look forward to a future where the big and little cores have the same ISA?
>R: We are working on that. Do they have to have the same ISA? Ronak and the team are looking at that. However I think our goal here is to keep the software as simple as possible for developers and customers. It's a challenge that our architects have taken up to ensure products like this enter the market smoothly. We’ll also have a packaging discussion next year on products like this. The chip you see today, while it was designed primarily for a particular customer to begin with, it’s not a custom product, and in that sense will be available to other OEMs.
This seems like a big issue to me going foward. The Intel fuses off various ISA features on various architectures for market segmentation reasons or just doesn't put them in in the case of Atom means that they'll have a harder time of it if they want to pursue big.LITTLE.
- monocasa 8y agoIroncially, Atom also gets ISA extensions that don't make their way into the bigger cores too, like the Intel SHA extensions. I think the idea was that the bigger cores were already smart enough to not really get a benefit from dedicated SHA instructions, but the did help the simpler Atom cores. Of course that now means that the big cores arent a super set of the small cores, feature wise.
- vetinari 8y agoSHA extension is on the way into Icelake, so they will be superset again.
- blattimwind 8y agoRyzen shipped those extensions and they improve SHA performance quite a lot.
- stephencanon 8y agoMOVBE is another example that appeared in Atom years before it was available in "big" cores.
- NullPrefix 8y agoEasiest way to solve would be moving the process to BIG core on first use of unsupported feature.
- Symmetry 8y agoI'm far from an expert here but it sounds like you'd have to keep track of CPU extensions on a per core and per thread basis and I don't think most OSs actually do that.
- aidenn0 8y agoOr just catch an illegal instruction trap and move the thread to a big core if it's on a little core.
- jandrese 8y agoOr vice versa? The talk here was about how the specialized crypto hardware was only on the little core because it isn't necessary on the big one.
- blattimwind 8y agoThe Atom encryption engine stuff isn't in the micro-arch though. Afaik you'd use it via kernel APIs.
- brigade 8y agoThat would still need kernel support, so apps will randomly crash if you aren't using the latest patches (spoiler: some people won't be) Really, it's just a bad idea overall to have usermode visible microarchitectural differences between cores, as Samsung keeps demonstrating with their Exynos chips.