By: Brett (ggtgp.delete@this.yahoo.com), August 9, 2014 10:37 pm
Room: Moderated Discussions
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on August 9, 2014 1:36 pm wrote:
> Brett (ggtgp.delete@this.yahoo.com) on August 9, 2014 11:51 am wrote:
> >
> > For those that are designing 40 watt ARM64 chips there are no legacy 32 bit apps to support
> > in the laptop/desktop/server space.
>
> Christ, you people.
>
> You can't have it both ways. You try to argue that "ISA matters a lot for decoding", but
> then at the same time you try to argue that "ISA doesn't matter at all for users".
Not an ARM fan boy the way you assume.
I have in the past here called ARM32 crap, and said that Apple could dump ARM and no one would care, and with the change to ARM64 and Apple designed silicon that is exactly what Apple is doing.
Apple was not going to drag that antique random collection of brain damage into the future. An Intel style patent and implementation moat for brain damage has no benefits for Apple.
> The fact that there are no legacy apps is a problem, not a feature. It means that the platform
> has no testing, that applications are few and hard to find, and that applications and libraries
> are raw, untested and likely have more bugs. In this case is also means that there are no
> actual performance numbers to back up your ridiculous and unlikely claims.
And how would adding a ARM32 app shell to an ARM64 server help with reducing bugs and exploits, and make development faster and cheaper. A black hole for security exploits and bugs that would be.
> Seriously?
Yes.
> Do you seriously believe that the alleged performance and power advantage (and yes, it very much is alleged
> - I would even go as far as call it "drug-induced hallucinations" - so far nobody has come even close to
> Intel in the space you claim is so ripe for ARM64 in either performance or price) are so massive that users
> should/would ignore the fact that the break in ISA also causes a lot of real and inevitable problems?
In a few short years no one will care about ARM32, everything will be 64bit, even the phones will be dumping compatibility with 32bit.
> Guys, get a f*cking grip. It's quite clear that ISA matters at the low end, because when you are counting
> transistors, decode complexity really shows up. But only crazy and deluded people think that it all that
> noticeable in the server space. Which is not to say that such crazy and deluded people don't exist - the
> failed companies that were build up around that concept certainly show that such people do exist - but
> you need to spend a few seconds asking yourself whether you want to be counted in that group.
>
> Even if ISA complexity is noticeable in that space (and as mentioned, Intel has so far a pretty damn good record
> of showing that the x86 ISA isn't a problem, since it has successfully killed off every single competing RISC/EPIC/insert-crazy-idea-here
> architecture), why the hell do you then think that nothing else matters?
>
> ARM64 isn't that magical. MIPS and alpha were there before it with pretty similar "simple
> decoding". You're repeating arguments that didn't make sense the last time around, and that
> have been soundly disproven in that thing we call "the real world" (tm) or "the market".
Good points.
You realize of course that 20 years ago the RISC camp was split into a half dozen factions, none big enough to survive.
Sparc and Power will be dead in a few years, both will convert to ARM64, just like AMD is.
Hows that for a prediction.
There will be a full spectrum of ARM64 implementations from low to as high as Intel can go.
> I think ARM has a chance, but the arguments for it in this thread have been absolutely moronic. The
> performance claims about how much better ARM64 is over ARM32 seem to be based on Geekbench, for chrissake.
> Some of the other arguments have been about how relatively quickly ARM has improved, which is largely
> based on the fact that Cortex-A9 was a complete and utter disaster particularly from an uncore standpoint,
> so when people bandy about "40% improvement" and compare that to how Haswell didn't make as much of
> a difference, they are clearly not understanding how the ARM baseline was crap.
Agreed. Old Arm chips are pretty crap.
> Even now, people seem to think that Apple A7 is somehow a high-performance chip. It's not really
> all that impressive, and again, the whole "look at how great it is" seems to be based almost entirely
> on pure crap (geekbench). And absolutely none of that is relevant to the server market.
>
> No, if ARM has a chance, it's not because it will outperform intel server chips
> (I can pretty much guarantee it won't), it is because of other market forces.
You will be wrong, and sooner than you think possible. All it takes is for POWER to go ARM64.
> For example, there are a lot of customers who want to make sure that they have alternatives,
> and are worried about the fact that Intel is so crushingly dominant. Those customers don't
> necessarily care about ARM at all, just go back a few months to look at the POWER8 motherboard
> news etc, but that "we really worry about a monoculture" is very much a real issue.
>
> Similarly, there are a lot of chip companies that want to get a part of the market, and if you don't have
> the resources of Intel, it's really hard to compete in the x86 space. Because that complexity may not
> be a huge performance issue in the end, but it does mean that there is a fairly high bar of entry.
Another prediction:
In ten years AMD will not be making any x86 chips. And no one will care. Plenty of ARM64 choices.
So are you going to go down with the x86 ship, or jump on the ARM64 bandwagon. ;)
(By the time you jump it will be too late, so yes you will go down with x86. ;) ;) ;)
> So there are reasons for ARM to be successful. We saw it in the mobile space: the licensing
> was a big boon there, and resulted in the proliferation of infrastructure around ARM.
> But it really isn't about performance or even power. It's about other market issues.
>
> And if you really think that the decoder is the only part that is complicated, boy have I got a
> bridge to sell you. A high-performance IO subsystem isn't simple either. Yes, it's all PCIe these
> days, but go talk to hardware people about how easy it's to do high-performance PCIe, and I suspect
> they'll laugh at you. Or the memory subsystem. Or a good high-performance SMP fabric.
Intel does take a small hit for the instruction decoder, that moat is worth it to Intel.
Lots of companies are doing those other things that matter, on ARM64.
> And no, those aren't exactly "small details" in a server environment. That whole "uncore"
> that makes sure that you can efficiently receive network packets that get DMA'd to memory
> at not-cacheline-aligned boundaries? Not simple either. Or just getting multi-socket interrupt
> controllers that work well, and can both spread things out and steer things properly? Yeah,
> there's a lot of work there, both in hardware and in all that system code.
>
> And that's all just outside the core itself. Even inside the core, the instruction decoding
> is just one detail in the end. And a detail that you can tweak - like spending a lot of effort
> on the branch predictor, so your front end runs ahead better, and so that an extra cycle of
> decoding latency isn't so noticeable. Or perhaps have a separate decoded uop cache etc.
>
> And then when you make such an absolutely ridiculously huge deal about instruction
> decoding, you at the same time entirely ignore why the customer, who is the
> one paying for it all in the end, might care about backwards compatibility.
>
> Really?
Yes, no one is going to run Windows XP on a ARM64 box.
Just what sort of mystical advantage do you think the random collection of near non-existent ARM32/Thumb/Cortex server software could possibly help a ARM64 server.
Do you want to add an x86 compatibility mode to ARM64? Really? That is the only way to get any backwards compatibility that matters to anyone. We both realize how stupid that idea is.
> So I'm dead serious when I say that anybody who talks about the alleged huge advantages of simple decoding,
> but then blithely ignores the advantages of backwards compatibility, is a f*cking moron.
Yes backwards compatibility MATTERS for x86. For ARM64 servers it is merely a short term nuisance.
Yes the near complete lack of apps will hurt at first, but the bandwagon will gather steam and nothing will stop it.
> And there's a lot of those f*cking morons in this thread. Some of them double down on their stupidity
> by claiming that it's a big advantage that you can jettison all that legacy baggage.
It is a small advantage to jettison all that legacy baggage, every little bit helps.
> Linus "rant over" Torvalds
Brett, who is apparently a f*cking moron. ;) ;) ;)
> Brett (ggtgp.delete@this.yahoo.com) on August 9, 2014 11:51 am wrote:
> >
> > For those that are designing 40 watt ARM64 chips there are no legacy 32 bit apps to support
> > in the laptop/desktop/server space.
>
> Christ, you people.
>
> You can't have it both ways. You try to argue that "ISA matters a lot for decoding", but
> then at the same time you try to argue that "ISA doesn't matter at all for users".
Not an ARM fan boy the way you assume.
I have in the past here called ARM32 crap, and said that Apple could dump ARM and no one would care, and with the change to ARM64 and Apple designed silicon that is exactly what Apple is doing.
Apple was not going to drag that antique random collection of brain damage into the future. An Intel style patent and implementation moat for brain damage has no benefits for Apple.
> The fact that there are no legacy apps is a problem, not a feature. It means that the platform
> has no testing, that applications are few and hard to find, and that applications and libraries
> are raw, untested and likely have more bugs. In this case is also means that there are no
> actual performance numbers to back up your ridiculous and unlikely claims.
And how would adding a ARM32 app shell to an ARM64 server help with reducing bugs and exploits, and make development faster and cheaper. A black hole for security exploits and bugs that would be.
> Seriously?
Yes.
> Do you seriously believe that the alleged performance and power advantage (and yes, it very much is alleged
> - I would even go as far as call it "drug-induced hallucinations" - so far nobody has come even close to
> Intel in the space you claim is so ripe for ARM64 in either performance or price) are so massive that users
> should/would ignore the fact that the break in ISA also causes a lot of real and inevitable problems?
In a few short years no one will care about ARM32, everything will be 64bit, even the phones will be dumping compatibility with 32bit.
> Guys, get a f*cking grip. It's quite clear that ISA matters at the low end, because when you are counting
> transistors, decode complexity really shows up. But only crazy and deluded people think that it all that
> noticeable in the server space. Which is not to say that such crazy and deluded people don't exist - the
> failed companies that were build up around that concept certainly show that such people do exist - but
> you need to spend a few seconds asking yourself whether you want to be counted in that group.
>
> Even if ISA complexity is noticeable in that space (and as mentioned, Intel has so far a pretty damn good record
> of showing that the x86 ISA isn't a problem, since it has successfully killed off every single competing RISC/EPIC/insert-crazy-idea-here
> architecture), why the hell do you then think that nothing else matters?
>
> ARM64 isn't that magical. MIPS and alpha were there before it with pretty similar "simple
> decoding". You're repeating arguments that didn't make sense the last time around, and that
> have been soundly disproven in that thing we call "the real world" (tm) or "the market".
Good points.
You realize of course that 20 years ago the RISC camp was split into a half dozen factions, none big enough to survive.
Sparc and Power will be dead in a few years, both will convert to ARM64, just like AMD is.
Hows that for a prediction.
There will be a full spectrum of ARM64 implementations from low to as high as Intel can go.
> I think ARM has a chance, but the arguments for it in this thread have been absolutely moronic. The
> performance claims about how much better ARM64 is over ARM32 seem to be based on Geekbench, for chrissake.
> Some of the other arguments have been about how relatively quickly ARM has improved, which is largely
> based on the fact that Cortex-A9 was a complete and utter disaster particularly from an uncore standpoint,
> so when people bandy about "40% improvement" and compare that to how Haswell didn't make as much of
> a difference, they are clearly not understanding how the ARM baseline was crap.
Agreed. Old Arm chips are pretty crap.
> Even now, people seem to think that Apple A7 is somehow a high-performance chip. It's not really
> all that impressive, and again, the whole "look at how great it is" seems to be based almost entirely
> on pure crap (geekbench). And absolutely none of that is relevant to the server market.
>
> No, if ARM has a chance, it's not because it will outperform intel server chips
> (I can pretty much guarantee it won't), it is because of other market forces.
You will be wrong, and sooner than you think possible. All it takes is for POWER to go ARM64.
> For example, there are a lot of customers who want to make sure that they have alternatives,
> and are worried about the fact that Intel is so crushingly dominant. Those customers don't
> necessarily care about ARM at all, just go back a few months to look at the POWER8 motherboard
> news etc, but that "we really worry about a monoculture" is very much a real issue.
>
> Similarly, there are a lot of chip companies that want to get a part of the market, and if you don't have
> the resources of Intel, it's really hard to compete in the x86 space. Because that complexity may not
> be a huge performance issue in the end, but it does mean that there is a fairly high bar of entry.
Another prediction:
In ten years AMD will not be making any x86 chips. And no one will care. Plenty of ARM64 choices.
So are you going to go down with the x86 ship, or jump on the ARM64 bandwagon. ;)
(By the time you jump it will be too late, so yes you will go down with x86. ;) ;) ;)
> So there are reasons for ARM to be successful. We saw it in the mobile space: the licensing
> was a big boon there, and resulted in the proliferation of infrastructure around ARM.
> But it really isn't about performance or even power. It's about other market issues.
>
> And if you really think that the decoder is the only part that is complicated, boy have I got a
> bridge to sell you. A high-performance IO subsystem isn't simple either. Yes, it's all PCIe these
> days, but go talk to hardware people about how easy it's to do high-performance PCIe, and I suspect
> they'll laugh at you. Or the memory subsystem. Or a good high-performance SMP fabric.
Intel does take a small hit for the instruction decoder, that moat is worth it to Intel.
Lots of companies are doing those other things that matter, on ARM64.
> And no, those aren't exactly "small details" in a server environment. That whole "uncore"
> that makes sure that you can efficiently receive network packets that get DMA'd to memory
> at not-cacheline-aligned boundaries? Not simple either. Or just getting multi-socket interrupt
> controllers that work well, and can both spread things out and steer things properly? Yeah,
> there's a lot of work there, both in hardware and in all that system code.
>
> And that's all just outside the core itself. Even inside the core, the instruction decoding
> is just one detail in the end. And a detail that you can tweak - like spending a lot of effort
> on the branch predictor, so your front end runs ahead better, and so that an extra cycle of
> decoding latency isn't so noticeable. Or perhaps have a separate decoded uop cache etc.
>
> And then when you make such an absolutely ridiculously huge deal about instruction
> decoding, you at the same time entirely ignore why the customer, who is the
> one paying for it all in the end, might care about backwards compatibility.
>
> Really?
Yes, no one is going to run Windows XP on a ARM64 box.
Just what sort of mystical advantage do you think the random collection of near non-existent ARM32/Thumb/Cortex server software could possibly help a ARM64 server.
Do you want to add an x86 compatibility mode to ARM64? Really? That is the only way to get any backwards compatibility that matters to anyone. We both realize how stupid that idea is.
> So I'm dead serious when I say that anybody who talks about the alleged huge advantages of simple decoding,
> but then blithely ignores the advantages of backwards compatibility, is a f*cking moron.
Yes backwards compatibility MATTERS for x86. For ARM64 servers it is merely a short term nuisance.
Yes the near complete lack of apps will hurt at first, but the bandwagon will gather steam and nothing will stop it.
> And there's a lot of those f*cking morons in this thread. Some of them double down on their stupidity
> by claiming that it's a big advantage that you can jettison all that legacy baggage.
It is a small advantage to jettison all that legacy baggage, every little bit helps.
> Linus "rant over" Torvalds
Brett, who is apparently a f*cking moron. ;) ;) ;)
