Live data from Hacker News

Introducing architecture variants

discourse.ubuntu.com

41–50 of 152 posts

Re: Introducing architecture variants

#41
post #40
post #31

Can we please have an "apt rollback" function?

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

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

Re: Introducing architecture variants

#42
post #8

Earlier quoted context omitted.

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

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…

Don't have a clear opinion, but you have to factor in all the issues that can be due to different versions of software. Think of unexposed bugs in the whole stack (that can include compiler bugs but also software bugs related to numerical computation or just uninitialized memory). There are enough heisenbugs without worrying that half the servers run on a slightly different software.

It's not for nothing that some time ago "write once, run everywhere" was a selling proposition (not that it was actually working in all cases, but definitely working better than alternatives).

Re: Introducing architecture variants

#43
post #17

> 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?

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.

Re: Introducing architecture variants

#44
post #8
post #5

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."

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

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.

Re: Introducing architecture variants

#45

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…

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.

Re: Introducing architecture variants

#46

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…

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.

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.

Re: Introducing architecture variants

#47
post #36
post #20

Earlier quoted context omitted.

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

1% is less than the difference between negotiating with a hangover or not.

What a strange comparison.

If you're negotiating deals worth billions of dollars, or even just millions, I'd strongly suggest not doing so with a hangover.

Re: Introducing architecture variants

#49
post #47
post #36

Earlier quoted context omitted.

1% is less than the difference between negotiating with a hangover or not.

What a strange comparison. If you're negotiating deals worth billions of dollars, or even just millions, I'd strongly suggest not doing so with a hangover.

> If you're negotiating deals worth billions of dollars, or even just millions, I'd strongly suggest not doing so with a hangover.

...have you met salespeople? Buying lap dances is a legitimate business expense for them. You'd be surprised how much personal rapport matters and facts don't.

In all fairness, I only know about 8 and 9 figure deals, maybe at 10 and 11 salespeople grow ethics...

Re: Introducing architecture variants

#50

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.

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.
Post reply on HN