Linux 5.18 Released With Intel SDSi, New CPU & GPU Features

[phoronix]

Phoronix: Linux 5.18 Released With Intel SDSi, New CPU & GPU Features

Linus Torvalds just released Linux 5.18 on-time as the newest stable kernel release...

https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.18-Released

[joshx1]

I see that there is work around the EPYC & NUMA, Threadripper 2990WX for example has NUMA as well (though not sure how related to EPYC it is?), would this also have an uplift out-of-the-box, or would there need to be patches made for that?

[Solid State Brain]

Is the Hardware Feedback Interface (HFI) ready to be taken advantage of by Intel Alder Lake processors or is more work needed for actually enabling it despite already being in the kernel?

[birdie]

Is the Hardware Feedback Interface (HFI) ready to be taken advantage of by Intel Alder Lake processors or is more work needed for actually enabling it despite already being in the kernel?

There has to be a userspace process/daemon/service which manages tasks and no one has created it. The kernel feature by itself is quite useless.

[NobodyXu]

There has to be a userspace process/daemon/service which manages tasks and no one has created it. The kernel feature by itself is quite useless.

Can't the task scheduler in kernel directly take advantage of HFI?

[birdie]

Can't the task scheduler in kernel directly take advantage of HFI?

I doubt that. In Windows something notifies the kernel which process is in foreground/background and the kernel then decides which cores this process could/should use. The Linux kernel has no notion of background/foreground processes, it doesn't know that your web browser is more important than some compilation/rendering/compute/etc. background task either. Moving these features into the kernel scheduler is a strict no-go.

[Volta]

Can't the task scheduler in kernel directly take advantage of HFI?

It can:

The kernel or a userspace policy daemon can use these capabilities to modify task placement decisions. For instance, if either the performance or energy capabilities of a given logical processor becomes zero, it is an indication that the hardware recommends to the operating system to not schedule any tasks on that processor for performance or energy efficiency reasons, respectively.

https://www.kernel.org/doc/html/latest/x86/intel-hfi.html#implementation-details-for-linux

[NobodyXu]

I doubt that. In Windows something notifies the kernel which process is in foreground/background and the kernel then decides which cores this process could/should use. The Linux kernel has no notion of background/foreground processes, it doesn't know that your web browser is more important than some compilation/rendering/compute/etc. background task either. Moving these features into the kernel scheduler is a strict no-go.

It is indeed impossible for the kernel to know about foreground/background processes, but maybe we can use priority (nice value) + the type of the process as a way to differentiate interactive and batch processes?

Interactive processes often has a low nice value, batch processes often has a high nice value and sometimes set to SCHED_BATCH or SCHED_IDLE.

While it may not provide the best performance, it is at least better than not using HFI at all.

[NobodyXu]

It can:



https://www.kernel.org/doc/html/late...ails-for-linux

Hmmm, I don't think it says that HFI is used by the scheduler, so without direct support of HFI in the scheduler, we will still have to wait for distro support for it.

[birdie]

Volta continues to impress with uttering the things he absolutely doesn't know or understand.

Microsoft with its deep pockets and tens of thousands of excellent programmers spent almost a year optimizing the Windows 11 scheduler for ADL and in Linux it will work right away by itself ... magically I presume. No tuning, no rules, no intelligence required, it'll just work.