Exophase (exophase@gmail.com) on 12/15/11 wrote:
>Your response makes it sound as if we know nothing
>about ARM64 when we know pretty much everything about it.

Umm. Are you reading the same thread I am? Are you able to
read at all?

The whole (and only) point of the thread is power
efficiency. Read the damn subject line again.

We know absolutely nothing about what the upcoming ARM64
systems will be like from a power-efficiency standpoint.
Especially not if they are four-way decode and aim to be
performance-competitive with x86.

And no, I do not believe that 4-way ARM64 is going to be
equivalent to 4-way x86. That said, I also don't think that
the decoder is really the dominant factor in that kind of
environment anyway, so I think it's pretty much all
theoretical.

And seriously, I don't think you have any idea about
what ARM64 will look like from an energy efficiency POV.

So read the subject line again.

The only thing I reacted to was the usual Wilco "ARM
is mindlessly better" blather. I just tried to point out
that comparing decode rates on an instruction basis across
different architectures is insane, because the same
program doesn't even have the same number of instructions
across architectures.

And I don't know what the numbers are, but I doubt that
ARM64 will have all that many fewer instructions than
ARM. And I do think that x86 tends to have fewer, partly
due to immediates, partly due to mem-op (and mem-op-mem) operations, and partly due to addressing modes.

So what the hell are you arguing about? Are you seriously
saying that comparing instructions across architectures is
sane? If so, you are just crazy, and that is as true of
ARM64 as it is of ARM.

Or are you seriously saying that we know anything relevant
about ARM64 energy efficiency?

Regardless of what you are trying to argue, you seem to be
blathering.

Linus