Red Hat, Fedora, Suse & Canonical are all thinking about dropping support for pre-Haswell CPU's. Wonder if this happens to Arch distros too?

Here’s the link:

Just got me wondering if this happens to Arch based distributions too.

Anybody have any speculation on this?

It makes perfect sense for RedHat. Corporate customers would be pretty unlikely to still be running CPUs that old once the support window for RH 9 has ended.

I don’t think Fedora is considering the same thing though. The most recent proposal for Fedora I saw was that they were planning to add limited packages which would be available in v3 in addition to the current targets starting with Fedora 40.

Arch has also considered adding v3 and/or potential v4 builds of packages in addition but that hasn’t gotten all that much traction due to the workload it would add would to packagers currently.

I am not well versed in what Ubuntu or SuSe are planning. It is worth noting the SuSe and OpenSuSe are wholly separate though.

As far as I know, many distros are planning on adding the support in addition to, not as a replacement of.

This is what I found on Ubuntu:

They’ve already done some benchmarking of different builds of their kernel optimized for the different tiers of CPU’s and mostly the differences were unimportant except for a few cases. But I guess were they to implement this, it would not work on older machines. I was thinking Arch is more of a hobby build, not so server oriented, but I don’t claim to know for sure, but I thought it may not be affected.

I have 3 Haswell and 1 Sandy Bridge machines.

The question is “How will they implement it?”

It is possible to provide packages build for both feature levels the same way they can provide packages for both x86 and ARM. Adding support for the v3 feature level doesn’t definitively mean removing support for other feature levels.

This fellow here is comparing the two approaches, interesting:

I like glibc-hwcaps approach: oh, you have a newer CPU, here is the optimized binary in this path.

@mlytle0 For arch based distros there are a couple of full distros like CachyOS and repos like ALHP so you can try it out right now if you want.

Been using ALHP for a long time, and in practice there is not much of a speed-up for a day-to-day usage, but for certain workloads that I need for my job the difference is immense.

On the other hand, a lot of perfectly functional, older hardware will be deprecated, so not sure what to think about that.

Looked that up and found this command that tells what tier your machine is, where that might be ambiguous.

/lib/ --help

Mine comes back as a level 3, which of course, I already knew, but how much performance bump do you get in ordinary tasks?

Very little.

this topic was already discussed on the Arch Mailing list early in 2022.
The plan back then was to add additional v3 optimized packages but not all maintainers got on board with the idea because they don’t want to wait twice as long for their package updates to build.

My take from that is: It will definitely happen at some point. That other distributions now are preparing those packages should speed up Arch maintainers getting on board of the idea. Not sure if they will stick to the plan of providing it in addition or it will become the new default (if other distributions already go v3 or above, why should bleeding edge Arch still offer packages for older CPU’s? Some other project will definitely pick up that support, see Arch32 for example).

If you want to try optimized packages already, I am using ALHP repo’s for many months now (and since mid December he even offers v4 optimized repo’s which I am using since then):

The general real life performance gain is only noticeble in performance edge cases. I mostly game on my system, and with the v3 or v4 packages, I get stutterfree framerates in situations where I had quite some stuttering with the stock Arch packages (meaning I can set the last setting to ultra where before only very High was good). So yeah, feature level optimization does not hurt but it can definitely improve your experience in some cases.

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.