By: Michael S (already5chosen.delete@this.yahoo.com), July 11, 2013 11:22 am
Room: Moderated Discussions
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on July 11, 2013 10:57 am wrote:
> bakaneko (nyan.delete@this.hyan.wan) on July 11, 2013 12:02 am wrote:
> >
> > It doesn't matter for application developers,
> > because native code is only recommended for
> > isolated routines called from Java code. And
> > the last thing any programmer would do is
> > disable NEON.
>
> Any sane person will agree that AnTuTu is crap, and that using icc is odd.
>
> But that last statement of yours is laughably incorrect.
>
> No sane person uses NEON, because NEON isn't available in most ARM implementations. In
> fact, even if you only look at higher-end ARM ("They all have NEON, right?"), it turns
> out that NEON is an optional feature (idiotic ARM waffling, even for Cortex-A9), and
> isn't available in some reasonably common chips (ie Tegra 2 or the SPEAr chips).
>
> The thing is, ARM floating point and vector extensions remain a disaster. When they exist, they
> are often perfectly fine, but because you can't depend on them existing, many sane implementations
> simply cannot use them, or have to use them exclusively behind a library interface (which in
> turn tends to defeat all performance advantages except for very specific cases).
>
> Cue Wilco making excuses for bad architecture decisions in 3.. 2.. 1.. Last
> time I pointed out how screwed up this was, he went into denial mode and was
> spouting lies about how NEON is an architected standard in all modern cores.
>
> ARM remains the most fragmented architecture out there. It's not one architecture, it's a jumble of a handful
> of incompatible architectures that ARM has fooled people into thinking is one thing. And then the ARM people
> point fingers at how ugly x86 is because x86 is backwards compatible. F*cking clueless liars.
>
> Linus
I don't know enough about Android software development to have an educated opinion about whether Cortex-A chips without Neon are sufficiently common to cause problems or not (AFAIR, Tegra 2 market penetration was under 1%, but may be there are other SoCs like that).
However I like your line of thought.
What I don't like it's when you come here and defend Intel's decision to omit AVX in the Silvermont!
> bakaneko (nyan.delete@this.hyan.wan) on July 11, 2013 12:02 am wrote:
> >
> > It doesn't matter for application developers,
> > because native code is only recommended for
> > isolated routines called from Java code. And
> > the last thing any programmer would do is
> > disable NEON.
>
> Any sane person will agree that AnTuTu is crap, and that using icc is odd.
>
> But that last statement of yours is laughably incorrect.
>
> No sane person uses NEON, because NEON isn't available in most ARM implementations. In
> fact, even if you only look at higher-end ARM ("They all have NEON, right?"), it turns
> out that NEON is an optional feature (idiotic ARM waffling, even for Cortex-A9), and
> isn't available in some reasonably common chips (ie Tegra 2 or the SPEAr chips).
>
> The thing is, ARM floating point and vector extensions remain a disaster. When they exist, they
> are often perfectly fine, but because you can't depend on them existing, many sane implementations
> simply cannot use them, or have to use them exclusively behind a library interface (which in
> turn tends to defeat all performance advantages except for very specific cases).
>
> Cue Wilco making excuses for bad architecture decisions in 3.. 2.. 1.. Last
> time I pointed out how screwed up this was, he went into denial mode and was
> spouting lies about how NEON is an architected standard in all modern cores.
>
> ARM remains the most fragmented architecture out there. It's not one architecture, it's a jumble of a handful
> of incompatible architectures that ARM has fooled people into thinking is one thing. And then the ARM people
> point fingers at how ugly x86 is because x86 is backwards compatible. F*cking clueless liars.
>
> Linus
I don't know enough about Android software development to have an educated opinion about whether Cortex-A chips without Neon are sufficiently common to cause problems or not (AFAIR, Tegra 2 market penetration was under 1%, but may be there are other SoCs like that).
However I like your line of thought.
What I don't like it's when you come here and defend Intel's decision to omit AVX in the Silvermont!