Introducing architecture variants

https://discourse.ubuntu.com/t/introducing-architecture-variants-amd64v3-now-available-in-ubuntu-25-10/71312

by jnsgruk • 9 months ago

243 145 9 months ago

discourse.ubuntu.com

theandrewbailey3• 9 months ago

A reference for x86-64 microarchitecture levels: https://en.wikipedia.org/wiki/X86-64#Microarchitecture_level...

x86-64-v3 is AVX2-capable CPUs.

mananaysiempre• 9 months ago

Right, though compared to what one generally thinks of as an “AVX2-compatible” CPU, it curiously omits AES-NI and CLMUL (both relevant to e.g. AES-GCM). Yes, they are not technically part of AVX2, but they are present in all(?) the qualifying Intel and AMD CPUs (like many other technically-not-AVX2 stuff that did get included, like BMI or FMA3).

smlacy• 9 months ago

I presume the motivation is performance optimization? It would be more compelling to include some of the benefits in the announcement?

embedding-shape• 9 months ago

They do mention it in the linked announcement, although not really highlighted, just as a quick mention:

As a result, we’re very excited to share that in Ubuntu 25.10, some packages are available, on an opt-in basis, in their optimized form for the more modern x86-64-v3 architecture level
Previous benchmarks we have run (where we rebuilt the entire archive for x86-64-v3 57) show that most packages show a slight (around 1%) performance improvement and some packages, mostly those that are somewhat numerical in nature, improve more than that.

pushfoo• 9 months ago

ARM/RISC-V extensions may be another reason. If a wide-spread variant configuration exists, why not build for it? See: - RISC-V's official extensions[1] - ARM's JS-specific float-to-fixed[2]

1. https://riscv.atlassian.net/wiki/spaces/HOME/pages/16154732/... 2. https://developer.arm.com/documentation/dui0801/h/A64-Floati...

mobilio• 9 months ago

Announce was here: https://discourse.ubuntu.com/t/introducing-architecture-vari...

and key point: "Previous benchmarks we have run (where we rebuilt the entire archive for x86-64-v3 57) show that most packages show a slight (around 1%) performance improvement and some packages, mostly those that are somewhat numerical in nature, improve more than that."

juujian• 9 months ago

Are there any use cases where that 1% is worth any hassle whatsoever?

adgjlsfhk12• 9 months ago

it's very no uniform. 99% see no change, but 1% see 1.5-2x better performance

dehrmann2• 9 months ago

Anything at scale. 1% across FAANG is huge.

wongarsu• 9 months ago

If every computer built in the last decade gets 1% faster and all we have to pay for that is a bit of one-off engineering effort and a doubling of the storage requirement of the ubuntu mirrors that seems like a huge win

If you aren't convinced by your ubuntu being 1% faster, consider how many servers, VMs and containers run ubuntu. Millions of servers using a fraction of a percent less energy multiplies out to a lot of energy

Aissen• 9 months ago

You need 100 servers. Now you need to only buy 99. Multiply that by a million, and the economies of scale really matter.

PeterStuer• 9 months ago

A lott of improvements are very incremental. In agregate, they often compound and are vey significant.

If you would only accept 10x improvements, I would argue progress would be very small.

colechristensen2• 9 months ago

Very few people are in the situation where this would matter.

Standard advice: You are not Google.

I'm surprised and disappointed 1% is the best they could come up with, with numbers that small I would expect experimental noise to be much larger than the improvement. If you tell me you've managed a 1% improvement you have to do a lot to convince me you haven't actually made things 5% worse.

wat10000• 9 months ago

It's rarely going to be worth it for an individual user, but it's very useful if you can get it to a lot of users at once. See https://www.folklore.org/Saving_Lives.html

"Well, let's say you can shave 10 seconds off of the boot time. Multiply that by five million users and thats 50 million seconds, every single day. Over a year, that's probably dozens of lifetimes. So if you make it boot ten seconds faster, you've saved a dozen lives. That's really worth it, don't you think?"

I put a lot of effort into chasing wins of that magnitude. Over a huge userbase, something like that has a big positive ROI. These days it also affects important things like heat and battery life.

The other part of this is that the wins add up. Maybe I manage to find 1% every couple of years. Some of my coworkers do too. Now you're starting to make a major difference.

rossjudson• 9 months ago

Any hyperscaler will take that 1% in a heartbeat.

locknitpicker• 9 months ago

Are there any use cases where that 1% is worth any hassle whatsoever?

I don't think this is a valid argument to make. If you were doing the optimization work then you could argue tradeoffs. You are not, Canonical is.

Your decision is which image you want to use, and Canonical is giving you a choice. Do you care about which architecture variant you use? If you do, you can now pick the one that works best for you. Do you want to win an easy 1% performance gain? Now you have that choice.

gwbas1c• 9 months ago

some packages, mostly those that are somewhat numerical in nature, improve more than that

Perhaps if you're doing CPU-bound math you might see an improvement?

ilaksh• 9 months ago

They did say some packages were more. I bet some are 5%, maybe 10 or 15. Maybe more.

Well one example could be llama.cpp . It's critical for them to use every single extension the CPU has move more bits at a time. When I installed it I had to compile it.

This might make it more practical to start offering OS packages for things like llama.cpp

I guess people that don't have newer hardware aren't trying to install those packages. But maybe the idea is that packages should not break on certain hardware.

Blender might be another one like that which really needs the extensions for many things. But maybe you so want to allow it to be used on some oldish hardware anyway because it still has uses that are valid on those machines.

godelski• 9 months ago

  > where that 1% is worth any hassle

You'll need context to answer your question, but yes there are cases.

Let's say you have a process that takes 100hrs to run and costs $1k/hr. You save an hour and $1k every time you run the process. You're going to save quite a bit. You don't just save the time to run the process, you save literal time and everything that that costs (customers, engineering time, support time, etc).

Let's say you have a process that takes 100ns and similarly costs $1k/hr. You now run in 99ns. Running the process 36 million times is going to be insignificant. In this setting even a 50% optimization probably isn't worthwhile (unless you're a high frequency trader or something)

This is where the saying "premature optimization is the root of all evil" comes from! The "premature" part is often disregarded and the rest of the context goes with it. Here's more context to Knuth's quote[0].

  There is no doubt that the holy grail of efficiency leads to abuse. Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.

  Yet we should not pass up our opportunities in that critical 3%. A good programmer will not be lulled into complacency by such reasoning, he will be wise to look carefully at the critical code; but only after that code has been identified.

Knuth said: "Get a fucking profiler and make sure that you're optimizing the right thing". He did NOT say "don't optimize".

So yes, there are plenty of times where that optimization will be worthwhile. The percentages don't mean anything without the context. Your job as a programmer is to determine that context. And not just in the scope of your program, but in the scope of the environment you expect a user to be running on. (i.e. their computer probably isn't entirely dedicated to your program)

[0] https://dl.acm.org/doi/10.1145/356635.356640 (alt) https://sci-hub.se/10.1145/356635.356640

ninkendo• 9 months ago

show that most packages show a slight (around 1%) performance improvement

This takes me back to arguing with Gentoo users 20 years ago who insisted that compiling everything from source for their machine made everything faster.

The consensus at the time was basically "theoretically, it's possible, but in practice, gcc isn't really doing much with the extra instructions anyway".

Then there's stuff like glibc which has custom assembly versions of things like memcpy/etc, and selects from them at startup. I'm not really sure if that was common 20 years ago but it is now.

It's cool that after 20 years we can finally start using the newer instructions in binary packages, but it definitely seems to not matter all that much, still.

Amadiro• 9 months ago

It's also because around 20 years ago there was a "reset" when we switched from x86 to x86_64. When AMD introduced x86_64, it made a bunch of the previously optional extension (SSE up to a certain version etc) a mandatory part of x86_64. Gentoo systems could already be optimized before on x86 using those instructions, but now (2004ish) every system using x86_64 was automatically always taking full advantage of all of these instructions*.

Since then we've slowly started accumulating optional extensions again; newer SSE versions, AVX, encryption and virtualization extensions, probably some more newfangled AI stuff I'm not on top of. So very slowly it might have started again to make sense for an approach like Gentoo to exist**.

* usual caveats apply; if the compiler can figure out that using the instruction is useful etc.

** but the same caveats as back then apply. A lot of software can't really take advantage of these new instructions, because newer instructions have been getting increasingly more use-case-specific; and applications that can greatly benefit from them will already have alternative code-pathes to take advantage of them anyway. Also a lot of the stuff happening in hardware acceleration has moved to GPUs, which have a feature discovery process independent of CPU instruction set anyway.

oivey• 9 months ago

This should build a lot more incentive for compiler devs to try and use the newer instructions. When everyone uses binaries compiled without support for optional instruction sets, why bother putting much effort into developing for them? It’ll be interesting to see if we start to see more of a delta moving forward.

ploxiln• 9 months ago

FWIW the cool thing about gentoo was the "use-flags", to enable/disable compile-time features in various packages. Build some apps with GTK or with just the command-line version, with libao or pulse-audio, etc. Nowadays some distro packages have "optional dependencies" and variants like foobar-cli and foobar-gui, but not nearly as comprehensive as Gentoo of course. Learning about some minor custom CFLAGS was just part of the fun (and yeah some "funroll-loops" site was making fun of "gentoo ricers" way back then already).

I used Gentoo a lot, jeez, between 20 and 15 years ago, and the install guide guiding me through partitioning disks, formatting disks, unpacking tarballs, editing config files, and running grub-install etc, was so incredibly valuable to me that I have trouble expressing it.

harha• 9 months ago

Would it make a difference if you compile the whole system vs. just the programs you want optimized?

As in, are there any common libraries or parts of the system that typically slow things down, or was this more targeting a time when hardware was more limited so improving all would have made things feel faster in general.

suprjami• 9 months ago

I somehow have the memory that there was an extremely narrow time window where the speedup was tangible and quantifiable for Gentoo, as they were the first distro to ship some very early gcc optimisation. However it's open source software so every other distro soon caught up and became just as fast as Gentoo.

hajile• 9 months ago

According to this[0] study of the Ubuntu 16.04 package repos, 89% of all x86 code was instructions were just 12 instructions (mov, add, call, lea, je, test, jmp, nop, cmp, jne, xor, and -- in that order).

The extra issue here is that SIMD (the main optimization) simply sucks to use. Auto-vectorization has been mostly a pipe dream for decades now as the sufficiently-smart compiler simply hasn't materialized yet (and maybe for the same reason the EPIC/Itanium compiler failed -- deterministically deciding execution order at compile time isn't possible in the abstract and getting heuristics that aren't deceived by even tiny changes to the code is massively hard).

Doing SIMD means delving into x86 assembly and all it's nastiness/weirdness/complexity. It's no wonder that devs won't touch it unless absolutely necessary (which is why the speedups are coming from a small handful of super-optimized math libraries). ARM vector code is also rather Byzantine for a normal dev to learn and use.

We need a more simple assembly option that normal programmers can easily learn and use. Maybe it's way less efficient than the current options, but some slightly slower SIMD is still going to generally beat no SIMD at all.

[0] https://oscarlab.github.io/papers/instrpop-systor19.pdf

pizlonator• 9 months ago

That 1% number is interesting but risks missing the point.

I bet you there is some use case of some app or library where this is like a 2x improvement.

alternatex• 9 months ago

Aggregated metrics are always useless as they tend to show interesting and sometimes exciting data that in actuality contains zero insight. I'm always weary of people making decisions based on aggregate metrics.

Would be nice to know the per app metrics.

dang• 9 months ago

Thanks - we've merged the comments from https://news.ycombinator.com/item?id=45772579 into this thread, which had that original source.

jwrallie• 9 months ago

Is it worth it losing the ability to just put your hdd on your older laptop and booting it in an emergency?

horizion2025• 9 months ago

How many additions have there even been outside of AVX-x? And even AVX-2 is from 2011. If we ignore AVX-x the last I can recall are the few instructions added in the manipulation sets BMI/ABM, but they are Haswell/Piledriver/Jaguar era (2012-2013). While some specific cases could benefit, doesn't seem like a goldmine of performance improvements.

Further, maybe it has not been a focus for compiler vendors to generate good code for these higher-level archs if few are using the feature. So Ubuntu's move could improve that.

theandrewbailey3• 9 months ago

A reference for x86-64 microarchitecture levels: https://en.wikipedia.org/wiki/X86-64#Microarchitecture_level...

x86-64-v3 is AVX2-capable CPUs.

jsheard2• 9 months ago

x86-64-v3 is AVX2-capable CPUs.

Which unfortunately extends all the way to Intels newest client CPUs since they're still struggling to ship their own AVX512 instructions, which are required for v4. Meanwhile AMD has been on v4 for two generations already.

theandrewbailey3• 9 months ago

At least Intel and AMD have settled on a mutually supported subset of AVX-512 instructions.

physicsguy3• 9 months ago

This is quite good news but it’s worth remembering that it’s a rare piece of software in the modern scientific/numerical world that can be compiled against the versions in distro package managers, as versions can significantly lag upstream months after release.

If you’re doing that sort of work, you also shouldn’t use pre-compiled PyPi packages for the same reason - you leave a ton of performance on the table by not targeting the micro-architecture you’re running on.

colechristensen2• 9 months ago

Most of the scientific numerical code I ever used had been in use for decades and would compile on a unix variant released in 1992, much less the distribution version of dependencies that were a year or two behind upstream.

owlbite• 9 months ago

Very true, but a lot of stuff builds on a few core optimized libraries like BLAS/LAPACK, and picking up a build of those targeted at a modern microarchitecture can give you 10x or more compared to a non-targeted build.

That said, most of those packages will just read the hardware capability from the OS and dispatch an appropriate codepath anyway. You maybe save some code footprint by restricting the number of codepaths it needs to compile.

physicsguy3• 9 months ago

I mean that’s just lucky and totally depends on your field and what is normal - just as an example, we used the LLNL SUNDIALS package for implicit time integration. On Ubuntu 24.04 the latest version is 6.4.1 where the latest published is v7.5.0. We found their major version releases tended to require changes.

There’s also the difference between being able to run and being able to run optimised. At least 5 years ago, the Ubuntu/Debian builds of FFTW didn’t include the parallelised OpenMP library.

In a past life I did HPC support and I recommend the Spack package manager a lot to people working in this area because you can get optimised builds with whatever compiler tool chain and options you need quite easily that way.

niwtsol• 9 months ago

Thanks for sharing this. I'd love to learn more about micro-architectures and instruction sets - would you have any recommendations for books or sources that would be a good starting place?

physicsguy3• 9 months ago

My experience is mostly practical really - the trick is to learn how to compile stuff yourself.

If you do a typical: "cmake . && make install" then you will often miss compiler optimisations. There's no standard across different packages so you often have to dig into internals of the build system and look at the options provided and experiment.

Typically if you compile a C/C++/Fortran .cpp/.c/.fXX file by hand, you have to supply arguments to instruct the use of specific instruction sets. -march=native typically means "compile this binary to run with the maximum set of SIMD instrucitons that my current machine supports" but you can get quite granular doing things like "-march=sse4,avx,avx2" for either compatibility reasons or to try out subsets.

jeffbee3• 9 months ago

I wonder who downvoted this. The juice you are going to get from building your core applications and libraries to suit your workload are going to be far larger than the small improvements available from microarchitectural targeting. For example on Ubuntu I have some ETL pipelines that need libxml2. Linking it statically into the application cuts the ETL runtime by 30%. Essentially none of the practices of Debian/Ubuntu Linux are what you'd choose for efficiency. Their practices are designed around some pretty old and arguably obsolete ideas about ease of maintenance.

PaulHoule2• 9 months ago

My RSS reader trains a model every week or so and takes 15 minutes total with plain numpy, scikit-learn and all that. Intel MKL can do the same job in about half the time as the default BLAS. So you are looking at a noticeable performance boost but zero bullshit install with uv is worth a lot. If I was interested in improving the model than yeah I might need to train 200 of them interactively and I’d really feel the difference. Thing is the model is pretty good as it is and to make something better I’d have to think long and hard about what ‘better’ means.

ciaranmca• 9 months ago

Out of interest, what reader is this? Sounds interesting

zipy124• 9 months ago

Yup, if you're using OpenCV for instance compiling instead of using pre-built binaries can result in 10x or more speed-ups once you take into account avx/threading/math/blas-libraries etc...

oofbey• 9 months ago

Yup. The irony is that the packages which are difficult to build are the ones that most benefit from custom builds.

zozbot2342• 9 months ago

What are the changes to dpkg and apt? Are they being shared with Debian? Could this be used to address the pesky armel vs. armel+hardfloat vs. armhf issue, or for that matter, the issue of i486 vs. i586 vs. i686 vs. the many varieties of MMX and SSE extensions for 32-bit?

(There is some older text in the Debian Wiki https://wiki.debian.org/ArchitectureVariants but it's not clear if it's directly related to this effort)

Denvercoder9• 9 months ago

Even if technically possible, it's unlikely this will be used to support any of the variants you mentioned in Debian. Both i386 and armel are effectively dead: i386 is reduced to a partial architecture only for backwards compatibility reasons, and armel has been removed entirely from development of the next release.

zozbot2342• 9 months ago

What you said is correct wrt. official support, but Debian also has an unofficial ports infrastructure that could be repurposed towards enabling Debian for older architecture variants.

bobmcnamara• 9 months ago

This would allow mixing armel and softvfp ABIs, but not hard float ABIs, at least across compilation unit boundaries (that said, GCC never seems to optimize ABI bottlenecks within a compilation unit anyway)

mwhudson4• 9 months ago

Could this be used to address the pesky armel vs. armel+hardfloat vs. armhf issue

No, because those are different ABIs (and a debian architecture is really an ABI)

the issue of i486 vs. i586 vs. i686 vs. the many varieties of MMX and SSE extensions for 32-bit?

It could be used for this but it's about 15 years too late to care surely?

(There is some older text in the Debian Wiki https://wiki.debian.org/ArchitectureVariants but it's not clear if it's directly related to this effort)

Yeah that is a previous version of the same design. I need to get back to talking to Debian folks about this.

dfc• 9 months ago

you will not be able to transfer your hard-drive/SSD to an older machine that does not support x86-64-v3. Usually, we try to ensure that moving drives between systems like this would work. For 26.04 LTS, we’ll be working on making this experience cleaner, and hopefully provide a method of recovering a system that is in this state.

Does anyone know what the plans are to accomplish this?

dmoreno• 9 months ago

If I were them I would make sure the V3 instructions are not used until late in the boot process, and some apt command that makes sure all installed programs are in the right subarchitecture for the running system, reinstalling as necessary.

But that does not sound like a simple for non technical users solution.

Anyway, non technical users using an installation on another lower computer? That sounds weird.

mwhudson4• 9 months ago

I am probably going to be the one implementing this and I don't know what I am going to do yet! At the very least we need the failure mode to be better (currently you get an OOPS when the init from the initrd dies due to an illegal instruction exception)

zer0zzz2• 9 months ago

There was a fat elf project to solve this problem at one point I thought.

DrNosferatu2• 9 months ago

Link?

mariusor• 9 months ago

Maybe parent is referring to icculus' FatELF proposal from fifteen years ago? https://icculus.org/fatelf/

stabbles• 9 months ago

Seems like this is not using glibc's hwcaps (where shared libraries were located in microarch specific subdirs).

To me hwcaps feels like a very unfortunate feature creep of glibc now. I don't see why it was ever added, given that it's hard to compile only shared libraries for a specific microarch, and it does not benefit executables. Distros seem to avoid it. All it does is causing unnecessary stat calls when running an executable.

mwhudson4• 9 months ago

No it's not using hwcaps. That would only allow optimization of code in shared libraries, would be irritating to implement in a way that didn't require touching each package that includes shared libraries and would (depending on details) waste a bunch of space on every users system. I think hwcaps would only make sense for a small number of shared libraries if at all, not a system wide thing.

sluongng• 9 months ago

Nice. This is one of the main reasons why I picked CachyOS recently. Now I can fallback to Ubuntu if CachyOS gets me stuck somewhere.

yohbho• 9 months ago

CachyOS uses this one percent of performance gains? Since it uses every performance gain, unsurprising. But now I wonder how my laptop from 2012 did run CachyOS, they seem to switch based on hardware, not during image download and boot.

topato• 9 months ago

correct, it just sets the repository in the pacman.conf to either cachyos, -v3, or -v4 during install time based on hardware probe

shmerl2• 9 months ago

Will Debian do it?

bmitch30202• 9 months ago

https://wiki.debian.org/ArchitectureVariants

shmerl2• 9 months ago

Hm, discussion is from 2023. Did anything come out of it?

amelius2• 9 months ago

Can we please have an "apt rollback" function?

riskable• 9 months ago

If you're using btrfs, you do get that feature: https://moritzmolch.com/blog/2506.html

o11c• 9 months ago

That fundamentally requires a snapshot-capable filesystem, so you need to use a distro designed around such.

amelius2• 9 months ago

Not necessarily. You can use the ptrace() system call to trace a process and store what it reads/writes into a journal, etc.

https://man7.org/linux/man-pages/man2/ptrace.2.html

julian-klode• 9 months ago

Yes sure

apt (3.1.7) unstable; urgency=medium . [ Julian Andres Klode ] * test-history: Adjust for as-installed testing . [ Simon Johnsson ] * Add history undo, redo, and rollback features

dima55• 9 months ago

Exciting. I just looked for docs about these new features, and can't find anything. Can you point us to these? Thanks!

benatkin• 9 months ago

There's an unofficial repo for ArchLinux: https://wiki.archlinux.org/title/Unofficial_user_repositorie...

Description: official repositories compiled with LTO, -march=x86-64-vN and -O3.

Packages: https://status.alhp.dev/

zdw• 9 months ago

Many other 3rd party software has already required x86-64-v2 or -v3 already.

I couldn't run something from NPM on a older NAS machine (HP Microserver Gen 7) recently because of this.

justahuman74• 9 months ago

If this goes well - will they do v4 as well?

jnsgruk• 9 months ago

Maybe - likely we’ll trade-off the added build/test/storage cost of maintaining each variant - so you might not see amd64v4, but possibly amd64v5 depending on how impactful they turn out to be.

The same will apply to different arm64 or riscv64 variants.

mwhudson4• 9 months ago

Probably not v4 unless AVX512 becomes more ubiquitous than it looks like it will. But yeah, I don't expect this to be the only variant ever.

skywhopper• 9 months ago

This sure feels like overkill that leaks massive complexity into a lot more areas than it’s needed in. For the applications that truly need sub-architecture variants, surely different packages or just some sort of meta package indirection would be better for everyone involved.

ElijahLynn• 9 months ago

I clicked on this article expecting an M series variant for Apple hardware...

westurner• 9 months ago

"Gentoo x86-64-v3 binary packages available" (2024) https://news.ycombinator.com/item?id=39255458

"Changes/Optimized Binaries for the AMD64 Architecture v2" (2025) https://fedoraproject.org/wiki/Changes/Optimized_Binaries_fo... :

Note that other distributions use higher microarchitecture levels. For example RHEL 9 uses x86-64-v2 as the baseline, RHEL 10 uses x86-64-v3, and other distros provide optimized variants (OpenSUSE, Arch Linux, Ubuntu).

whalesalad• 9 months ago

means to better exploit modern processors without compromising support for older hardware

very odd choice of words. "better utilize/leverage" is perhaps the right thing to say here.

JohnKemeny• 9 months ago

"exploit": make full use of and derive benefit from

Hasz• 9 months ago

Getting a 1% across the board general purpose improvement might sound small, but is quite significant. Happy to see Canonical invest more heavily in performance and correctness.

Would love to see which packages benefited the most in terms of percentile gain and install base. You could probably back out a kWh/tons of CO2 saved metric from it.

malkia• 9 months ago

This is awesome, but ... If you process requires deterministic results (speaking about floats/doubles mostly here), then you need to get this straight.

tommica• 9 months ago

Once they have rebuilt with rust, they get to move away from GPL licenses and get to monetize things.

rock_artist• 9 months ago

So if it got it right, This is mostly a way to have branches within a specific release for various levels of CPUs and their support of SIMD and other modern opcodes.

And if I have it right, The main advantage should come with package manager and open sourced software where the compiled binaries would be branched to benefit and optimize newer CPU features.

Still, this would be most noticeable mostly for apps that benefit from those features such as audio dsp as an example or as mentioned ssl and crypto.

jeffbee3• 9 months ago

I would expect compression, encryption, and codecs to have the least noticeable benefit because these already do runtime dispatch to routines suited to the CPU where they are running, regardless of the architecture level targeted at compile time.

WhyNotHugo• 9 months ago

OTOH, you can remove the runtime dispatching logic entirely if you compile separate binaries for each architecture variant.

Especially the binaries for the newest variant, since they can entirely conditionals/branching for all older variants.

brucehoult• 9 months ago

So now they can support RISC-V RVA20 and RVA23 in the same distro?

All the fuss about Ubuntu 25.10 and later being RVA23 only was about nothing?

snvzz• 9 months ago

They sure can, but it seems they simply did not want to.

watersb2• 9 months ago

Over the past year, Intel has pulled back from Linux development.

Intel has reduced its number of employees, and has lost lots of software developers.

So we lost Clear Linux, their Linux distribution that often showcased performance improvements due to careful optimization and utilization of microarchitectural enhancements.

I believe you can still use the Intel compiler, icc, and maybe see some improvements in performance-sensitive code.

https://clearlinux.org/

"It was actively developed from 2/6/2015-7/18/2025."

dooglius• 9 months ago

icc was discontinued FWIW. The replacement, icx, is AIUI just clang plus some proprietary plugins

watersb2• 9 months ago

I wonder how this relates to Intel's "One API", which extends a single C code base across the various CPU targets (such as the core ALU, base vector units, AVX-512, NPU) and Intel GPU accelerators.

Not the same thing, or perhaps an augmentation of Intel performance libraries (which required C++, I believe).

Sure, harmonizing all of this may have suggested that there were too many software teams. But device drivers don't write themselves, and without feedback from internal software developers, you can't validate your CPU designs.

wyldfire• 9 months ago

Would we have something like aarch64 neon/SVE too?

random29ah• 9 months ago

I'm really "new" to x64 (I only migrated from 32-bit in 2020...) and the difference I noticed between x86-64-v1 and x86-64-v3 was only with video (with ffmpeg), audio (mp3/ogg/mp4...) and encryption; the rest remains practically the same.

Naively, I believe it might be more appropriate to have x86-64-v1 and x86-64-vN options only for specific software and leave the rest as x86-64-v1.

AVX seemed to give the biggest boost to things.

Regarding those who are making fun of Gentoo users, it really did make a bigger difference in the past, but with the refinement of compilers, the difference has diminished. Today, for me, who still uses Gentoo/CRUX for some specific tasks, what matters is the flexibility to enable or disable what I want in the software, and not so much the extra speed anymore.

As an example, currently I use -Os (x86-64-v1) for everything, and only for things related to video/sound/cryptography (I believe for things related to mathematics in general?) I use -O2 (x86-64-v3) with other flags to get a little more out of it.

Interestingly, in many cases -Os with -mtune=nocona generates faster binaries even though I'm only using hardware from Haswell to today's hardware (who can understand the reason for this?).

Introducing architecture variants

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