By: -.- (blarg.delete@this.mailinator.com), September 25, 2021 5:35 pm
Room: Moderated Discussions
Andrey (andrey.semashev.delete@this.gmail.com) on September 25, 2021 4:46 am wrote:
> Again, you're talking about the spec, and I'm talking about the actual hardware. If all or the absolute
> majority of implementations don't care about alignment then that's great and developers don't need
> to optimize for it. But we don't have that many SVE implementations, and for other kind of instructions
> real hardware does care about alignment, so I'm going do assume SVE won't be an exception. Hardware
> designers will have to prove that alignment doesn't matter, they haven't done that yet.
Both matter. It doesn't matter what properties the hardware has if the software doesn't take advantage of it.
I very much believe alignment is a thing in hardware. But all that is for naught if no-one actually writes code with that in consideration (which is something the SVE spec seems to encourage).
> Rumor has it that AMD is also working on a hybrid CPU, possibly in Zen 5. I
> think, eventually hybrid designs will settle in x86 desktops and servers.
Not sure about servers (even ARM doesn't do heterogeneous cores there), but it does make sense for client systems.
> AMD SkyBridge (https://www.extremetech.com/computing/181867-amds-project-skybridge-new-arm-and-x86-chips-that-are-pin-compatible)
> though was in the works. I imagine, in multi-socket systems you could use both x86 and ARM cores
> together. The project is dead now, so we probably will never know.
Nothing says you can run the two together, and I see basically no advantage in introducing such ridiculous complexity to enable such.
> Again, you're talking about the spec, and I'm talking about the actual hardware. If all or the absolute
> majority of implementations don't care about alignment then that's great and developers don't need
> to optimize for it. But we don't have that many SVE implementations, and for other kind of instructions
> real hardware does care about alignment, so I'm going do assume SVE won't be an exception. Hardware
> designers will have to prove that alignment doesn't matter, they haven't done that yet.
Both matter. It doesn't matter what properties the hardware has if the software doesn't take advantage of it.
I very much believe alignment is a thing in hardware. But all that is for naught if no-one actually writes code with that in consideration (which is something the SVE spec seems to encourage).
> Rumor has it that AMD is also working on a hybrid CPU, possibly in Zen 5. I
> think, eventually hybrid designs will settle in x86 desktops and servers.
Not sure about servers (even ARM doesn't do heterogeneous cores there), but it does make sense for client systems.
> AMD SkyBridge (https://www.extremetech.com/computing/181867-amds-project-skybridge-new-arm-and-x86-chips-that-are-pin-compatible)
> though was in the works. I imagine, in multi-socket systems you could use both x86 and ARM cores
> together. The project is dead now, so we probably will never know.
Nothing says you can run the two together, and I see basically no advantage in introducing such ridiculous complexity to enable such.