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Why is Rosetta 2 fast?

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Re: Why is Rosetta 2 fast?

#231

Post by rowanG077 »

freedomben wrote: post #83
hinkley wrote: post #15

I remember years ago when Java adjacent research was all the rage, HP had a problem that was “Rosetta lite” if you will. They had a need to run old binaries on new hardware that wasn’t exactly backward compatible. They made a transpiler that worked on binaries. It might have even been a JIT but that part of the memory is fuzzy. What made it interesting here was that as a sanity check they made an A->A mode where they…

If JIT-ing a statically compiled input makes it faster, does that mean that JIT-ing itself is superior or does it mean that the static compiler isn't outputting optimal code? (real question. asked another way, does JIT have optimizations it can make that a static compiler can't?)

A JIT can definitely make optimizations that a static compiler can't. Simply by virtue of it having concrete dynamic real-time information.

Re: Why is Rosetta 2 fast?

#232

Post by fredoralive »

masklinn wrote: post #27
stu2b50 wrote: post #12

Earlier quoted context omitted.

Rosetta 1 had a ticking time bomb. Apple was licensing it from a 3rd party. Rosetta 2 is all in house as far as we know. Different CEO as well. Jobs was more opinionated on “principles” - Cook is more than happy to sell what people will buy. I think Rosetta 2 will last.

> Rosetta 1 had a ticking time bomb. Apple was licensing it from a 3rd party. Yes, I'm sure Apple had no way of extending the license. > Cook is more than happy to sell what people will buy. I think Rosetta 2 will last. There's no "buy" here. Rosetta is complexity to maintain, and an easy cut. It's not even part of the base system. And “what people will buy” certainly didn’t prevent essentially removing support for n…

What do you mean non HiDPI display support being removed from Mac OS? I’ve been using a pair of 1920x1080 monitors with my Mac Mini M1 just fine? Have they somehow broken something in Mac OS 13 / Ventura? (I haven’t clicked the upgrade button yet, I prefer to let others leap boldly first).

Re: Why is Rosetta 2 fast?

#233

Post by klelatti »

Vt71fcAqt7 wrote: post #38
masklinn wrote: post #6

Earlier quoted context omitted.

> I hope Rosetta is here to stay and continues developement. It almost certainly is not. Odds are Apple will eventually remove Rosetta II, as they did Rosetta back in the days, once they consider the need for that bridge to be over (Rosetta was added in 2006 in 10.4, and removed in 2011 from 10.7). > And I hope what is learned from it can be used to make a RISC-V version of it. translating native ARM to RISC-V should…

>That's not going to happen unless Apple decides to switch from ARM to RISC-V, and... why would they? They've got 15 years experience and essentially full control on ARM. Two points here. • First off, Apple developers are not binded to Apple. The knkwledge gained can be used elsewhere. See Rivos and Nuvia for example. • Second, Apple reportedly has already ported many of it's secondary cores to RISC-V. It's not unrea…

> it’s not unreasonable that they will switch in 10 years or so.

You’ve not provided any rationale at all for why they should switch their application cores let alone on this specific timetable.

Switching is an expensive business and there has to be a major business benefit for Apple in return.

Re: Why is Rosetta 2 fast?

#234

Post by rowanG077 »

arianvanp wrote: post #180
nicoburns wrote: post #30

Earlier quoted context omitted.

> If so, does it affect the application startup times? It does, but only the very first time you run the application. The result of the transpilation is cached so it doesn't have to be computed again until the app is updated.

And deleting the cache is undocumented (it is not in the file system) so if you run Mac machines as CI runners they will trash and brick themselves running out of disk space over time.

What in the actual fuck. That is such an insane decision. Where is it stored then? Some dark corner of the file system inaccessible via normal means?

Re: Why is Rosetta 2 fast?

#235

Post by lmm »

astrange wrote: post #209
hamstergene wrote: post #123

Earlier quoted context omitted.

Could it be simply because many binaries were produced by much older, outdated optimizers. Or optimized for size. Also, optimizers usually target “most common denominator” so native binaries rarely use full power of current instruction set. Jumping from that peculiar finding to praising runtime JIT feels like a longshot. To me it’s more of an argument towards distributing software in intermediate form (like Apple Bit…

> To me it’s more of an argument towards distributing software in intermediate form (like Apple Bitcode) and compiling on install, tailoring for the current processor. This turns out to be quite difficult, especially if you're using bitcode as a compiler IL. You have to know what the right "intermediate" level is; if assumptions change too much under you then it's still too specific. And it means you can't use things…

> This turns out to be quite difficult, especially if you're using bitcode as a compiler IL. You have to know what the right "intermediate" level is; if assumptions change too much under you then it's still too specific. And it means you can't use things like inline assembly.

> That's why bitcode is dead now.

Isn't this what Android does today? Applications are distributed in bytecode form and then optimized for the specific processor at install time.

Re: Why is Rosetta 2 fast?

#236

Post by gumby »

masklinn wrote: post #94
gumby wrote: post #67

Earlier quoted context omitted.

> That's not going to happen unless Apple decides to switch from ARM to RISC-V, and... why would they? They've got 15 years experience and essentially full control on ARM. 15? More than a quarter century. They were one of the original investors in ARM and have produced plenty of arm devices since then beyond the newton and the ipod. I’d bet they use a bunch of risc v internally too if they just need a little cpu to m…

> 15? More than a quarter century. They were one of the original investors in ARM and have produced plenty of arm devices since then beyond the newton and the ipod. They didn't design their own chips for most of that time.

At the same time as the ARM investment they had a Cray for...chip design.

Re: Why is Rosetta 2 fast?

#237

Post by rowanG077 »

Vt71fcAqt7 wrote: post #4

I hope Rosetta is here to stay and continues developement. And I hope what is learned from it can be used to make a RISC-V version of it. translating native ARM to RISC-V should be much easier than x86 to ARM as I understand it, so one could conceivably do x86 -> ARM -> RISC-V.

I hope not. Rosetta 2, as cool as it is, is a crutch to allow Apple to transition away from x86. If it keeps beeing needing it's a massive failure for Apple and the ecosystem.

Re: Why is Rosetta 2 fast?

#238

Post by Gigachad »

johnthuss wrote: post #2

"I believe there’s significant room for performance improvement in Rosetta 2... However, this would come at the cost of significantly increased complexity... Engineering is about making the right tradeoffs, and I’d say Rosetta 2 has done exactly that."

Would be a waste of effort when the tool is designed to be obsolete in a few years as everything gets natively compiled.

Re: Why is Rosetta 2 fast?

#239

Post by foobiekr »

mark_undoio wrote: post #132
hinkley wrote: post #15

I remember years ago when Java adjacent research was all the rage, HP had a problem that was “Rosetta lite” if you will. They had a need to run old binaries on new hardware that wasn’t exactly backward compatible. They made a transpiler that worked on binaries. It might have even been a JIT but that part of the memory is fuzzy. What made it interesting here was that as a sanity check they made an A->A mode where they…

Something that fascinates me about this kind of A -> A translation (which I associate with the original HP Dynamo project on HPPA CPUs) is that it was able to effectively yield the performance effect of one or two increased levels of -O optimization flag. Right now it's fairly common in software development to have a debug build and a release build with potentially different optimisation levels. So that's two builds…

One of the engineers I was working with on a project was from Transitive (the company that made QuickTransit which became Rosetta) found that their JIT based translator could not deliver significant performance increases for A->A outside of pathological cases, and it was very mature technology at the time.

I think it's a hypothetical. The Mill Computing lectures talk about a variant of this, which is sort of equivalent to an install-time specializer for intermediate code which might work, but that has many problems (for one thing, it breaks upgrades and is very, very problematic for VMs being run on different underlying hosts).

Re: Why is Rosetta 2 fast?

#240

Post by perardi »

dynjo wrote: post #17

It is quite astonishing how seamless Apple has managed to make the Intel to ARM transition, there are some seriously smart minds behind Rosetta. I honestly don't think I had a single software issue during the transition!

I think the end of support for 32-bit applications in 2019 helped, slightly, with the run-up.

Assuming you weren’t already shipping 64-bit applications…which would be weird…updating the application probably required getting everything into a contemporary version of Xcode, cleaning out the cruft, and getting it compiling nice and cleanly. After that, the ARM transition was kind of a “it just works” scenario.

Now, I’m sure Adobe and other high-performance application developers had to do some architecture-specific tweaks, but, gotta think Apple clued them in ahead of time as to what was coming.

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