Linux 6.12 Features Super Real-Time, Sched_ext, Intel Xe2 and Pi 5

79 pointsposted 14 hours ago
by rbanffy

32 Comments

simonask

an hour ago

As a musician, glad to see audio production mentioned as an important use case.

Even a 10 ms delay is noticeable when playing an instrument. A lot of processing is required to produce a sound: Receive the input over a hardware interface, send it into userspace, determine what sound to play - usually a very complicated calculation with advanced plugins - potentially accessing many megabytes of raw sound data, apply chains of effects, mix it all together, send megabytes of uncompressed sound data back to the kernel, and push it out through an audio interface.

The more predictable the kernel can be, the more advanced audio processing can be, and better music comes out. Every single microsecond counts.

Modern software instruments can emulate acoustic instruments with a high degree of precision and realism, and a huge range of expressive freedom, but that takes a lot of processing power in real time.

guenthert

10 minutes ago

I Dunno. "The main aim of the PREEMPT_RT patch is to minimize the amount of kernel code that is non-preemptible", that's nice and all, but there are still no guarantees, which (in some interpretation of "real time") a RTOS is all about. For some applications the effort might suffice, but others will insist on those guarantees. For music recordings, I (perhaps naively) would expect a decent audio card with its own processor and (RT) firmware would yield better results.

ziofill

13 hours ago

https://www.zdnet.com/article/20-years-later-real-time-linux...

This article explains well why PREEMPT_RT is a big deal and why it was so much work to get in into the kernel.

amelius

10 hours ago

Are there any good books or other resources yet on realtime programming on Linux?

7e

9 hours ago

That article claims that without NO_HZ Linux wouldn’t be running in datacenters. Um, no. Many hyperscalers still haven’t enabled it! Stopped reading there.

hamandcheese

13 hours ago

The Pi 5 support is surprising, or rather that it's only landing now.

haukem

12 hours ago

The Raspberry Pi Foundation does not do a good upstream support. It is not very bad, but also not good. They should start adding support for their new chips in the upstream projects before they get into the market, like Intel does it for example. They could add support for some new IP cores, without reveling when and how it will be used later. When the product comes out the only add small patches linking the code together like device tree files.

It would also be good if they would release all the closed source firmware files needed for their devices under a redistributable license in the linux-firmware repository. For some time it was not allowed to redistribute the binary wifi firmware needed for the Raspberry Pi devices. This is needed for Linux distributions to package the binaries.

I hope they do this only because of lack of resources and not intentionally to lock people into their Linux distribution.

jakjak123

10 hours ago

Its not awful, but its not good either. Pi4 has been a looooong slog, but they also use components that cant be released under GPL license, so there is not much they could upstream for those components

seba_dos1

2 hours ago

Virtually nobody uses mainline Linux on Raspberry Pis, so not sure why would it be so surprising.

master_crab

13 hours ago

If I went and checked commits, I’m sure there are a lot of business critical IOT/controller type processes that now rely on Raspberry and therefore engineers backing support out the gate

hamandcheese

13 hours ago

But it's not out of the gate, it's been almost a year.

master_crab

13 hours ago

All relative I guess. “Out the gate” for fairly conservative industrial controllers can probably be measured in months to years.

You never catch them using anything near latest in an application.

xattt

13 hours ago

Still waiting on SR-IOV for Xe graphics to make it…

Modules are available, but it’s hit-and-miss with updates.

beeflet

13 hours ago

Isn't intel SRIOV getting mainlined with Xe driver in 6.12 or am I mistaken?

xattt

11 hours ago

It’s a fairly significant feature but it’s not mentioned in the 6.12 pull notes. Various sites mention that it’s “definitely, for sure, this time” mainlined in the next release, but I haven’t seen anything definitive.

I’m just an end user, so I don’t know if it’s been mentioned in a newsgroup somewhere.

vamega

8 hours ago

Yeah, went through a whole journey getting this to work on a NixOS guest with a Proxmox host recently.

You reminded me to write up the process, and publish a flake for NixOS users who want the kernel.

eblanshey

13 hours ago

So Linux now officially support RTOS capabilities, without patches, which is pretty cool. I wonder, realistically, how many applications that were originally designed to use microcontrollers for real-time purposes, can be migrated to use Linux, which vastly simplifies and lowers the cost development. And having the ability to use high-level languages like Python significantly lowers the barrier to entry. Obviously certain applications require the speed of a MCU without an operating system, but how many projects really don't need dedicated MCUs?

elcritch

12 hours ago

Unfortunately migrating real-time stuff to Linux _doesn't_ necessarily reduce costs or simplify real-time development needs. I've been doing embedded development for 5+ years at a few companies and doing embedded Linux is still a slog. I prefer a good MCU running Nim or other modern language. Heck there's even MicroPython nowadays.

Especially for anything that needs to "just run" for multiple years. Linux means you must deal of the distro or something like Yocto or Buildroot. Both of which have major pain points.

eblanshey

10 hours ago

I would think the portability of, say, a Python application running on Linux is a nice benefit. Try switching from one MCU to a totally different one and you may have to start from scratch (e.g. try going from Microchip to STM.) Can you describe why embedded Linux is still a slog? And what do you think it would take for the issues to be addressed?

makapuf

3 hours ago

I thought we were talking about real-time applications, which I'm not sure Python is (even tuning the GC). But if we're talking about the difficulty of changing MCU families (remember stm32 are >1000 different chips) changing OS is also difficult, even changing from yocto to buildroot can also be a lot of pain on linux.

wongarsu

10 hours ago

Doesn't Micropython already get you 95% of the way towards just running the same Python code on multiple MCUs?

eblanshey

8 hours ago

I'm not sure, I've never used it. But I think the issue is that the number of MCUs that support micropython is very small.

magicalhippo

2 hours ago

MicroPython supports[1] PIC16 and SAMD21/SAMD51, STM32, ESP8266/ESP32 and more, but it also supports Zephyr as a target, and with it the platforms Zephyr supports[2].

So yeah not everything under the sun, but certainly not what I'd consider a "very small" number of MCUs.

Of course, support level varies among the platforms, but you're not going to be doing too fancy things in MicroPython I imagine.

[1]: https://github.com/micropython/micropython?tab=readme-ov-fil...

[2]: https://docs.zephyrproject.org/latest/boards/index.html

user

13 hours ago

[deleted]

7e

9 hours ago

Linux is boomer tech. It keeps up with the latest hardware, that’s about it. Even real time is decades old. I would rather hear about the latest crypto Ponzi scheme than the latest Linux release. At least that would be novel.

beeflet

6 hours ago

its what a kernels supposed to do. also cryptocurrency scams are not that novel in my experience, they're usually pretty derivative and low-effort

resource_waste

11 hours ago

Ubuntu/Debian/Mint family will get it, one day...

Reminded that Debian-family is outdated linux that uses the marketing 'stable' which has 0 relations to the number of bugs.

Modern Linux like Fedora has those bugs already fixed.

I say this as a warning. I thought we were trapped with Windows 11 and 'Linux'(meaning Debian-family). No, turns out that is outdated linux and Modern linux is amazing.

I'm a bit reluctant to lump Fedora in with 'Linux', because its not fair to Fedora.

yjftsjthsd-h

4 hours ago

> Reminded that Debian-family is outdated linux that uses the marketing 'stable' which has 0 relations to the number of bugs.

Correct: It is stable, which is to say that things that work today will work tomorrow and the system does its best to stay out of your way. It doesn't, say, expect you to jump major versions every 6 months like other distros you might name.

> I thought we were trapped with Windows 11 and 'Linux'(meaning Debian-family).

I mean, yeah, the family of Linux distros alone is huge; conflating "Linux" and "Debian-family" is a significant mistake.

> No, turns out that is outdated linux and Modern linux is amazing.

And less-bleeding-edge Linux is also amazing. Unless you need the new stuff, moving at a slightly more sedate pace is perfectly fine. Which way the tradeoffs go depends on you and your usecases; some people want all the new shiny features right right now and benefit from riding the bleeding edge (like Debian Sid, Arch, or yes Fedora), and some people want to set things up and then not have to think about that machine for another few years (funny enough, I'd actually prefer that Debian supported each release for an even longer time, but that takes resources the project doesn't have). Bashing either approach is myopic.

exe34

3 hours ago

I don't think I've ever had a Debian install crash. When they say stable, they mean stable.

jakjak123

10 hours ago

Yeah, I have been saying this for years now. Debian and Ubuntu type distros starts doing custom patches and cherry picks changes into 3 year old software, just to keep it chugging along. Sounds like insanity to me. Just upgrade so you are not 3-4 years behind, and by keeping the number of custom patching lower, have a simpler time fixing bugs.