Linus Torvalds (torvalds.delete@this.linux-foundation.org) on November 18, 2014 10:32 am wrote:
> someone (someone.delete@this.somewhere.com) on November 17, 2014 8:10 pm wrote:
> > >
> > > The fact that should make you extra embarrassed for it is
> > > that whole "Useful IPC counted using 'unstalled cycles'"
> > > part, which takes the whole "let's inflate our CPI" to absolutely
> > > ridiculous levels. You might even call it "lying",
> > > since it has absolutely nothing to do with "CPI", and even less to do with the word "useful".
> >
> > That is interesting information related to available ILP in the compiled code, not an evil plot.
>
> No it's not. And that's exactly what I'm arguing against. Christ,
> 'somebody', did you not even follow the whole argument?
>
> The whole issue was exactly that people doing wide machines lie to themselves and others, by ignoring
> the fact that those wide machines also lose a lot of instructions when they stall. That was what this all
> started with, and it wasn't even me who made the argument, I just replied "Amen" to Patrick Chase.
>
> And that Itanium paper is a perfect example of that kind of lying. It's talking
> up some theoretical IPC that has absolutely nothing to do with any reality,
> exactly by talking up the IPC and ignoring the costs of stalls.
>
> In reality, Itanium had no greater IPC than anybody else. Anybody who
> in a paper talks about IPC values in the 2+ range is simply lying.
>
> So give it up. You're the one who asked for examples from Intel or HP.
> I gave them to you. You're the one who cannot face reality here.
>
> This is classic VLIW apologia, and exactly what I was talking about. And yes, EPIC made it
> worse by making the instruction packing (let's not call it IPC, because it damn well isn't,
> whatever the Intel and HP performance engineers said!) look better by using speculation.
>
> Christ. Give it up. Why am I even responding to your crap?
>
> The fact is, Itanium had bad performance, and had worse IPC than an out-of-order machine woudl
> have had. People who claim it had good IPC were either lying (and dammit, that Intel/HP paper
> really is at least "actively misleading" by calling it "CPI", if you think the "L" word is
> too harsh). Often by ignoring the costs of stalls. Exactly like in that paper!.
>
> And when they weren't actively ignoring stalls and/or speculative
> instructions, they were ignoring the low frequency.
>
> Linus


So basically YOU don't like the way they described a sub-component of architectural
performance within a presentation. That makes THEM evil lying bastards regardless
of the fact that they fully document the context of that specific information to put it
into proper perspective? Wow!

You are a vindictive intellectually dishonest asshole and I am done with this thread.