Schedutil Frequency Invariance Revised For Better Intel Performance + Power Efficiency

[phoronix]

Phoronix: Schedutil Frequency Invariance Revised For Better Intel Performance + Power Efficiency

SUSE developer Giovanni Gherdovich has sent out the latest patches on supporting frequency invariance within the kernel's scheduler code and ultimately making use of it for select Intel CPUs to yield not only better raw performance but also power efficiency...

http://www.phoronix.com/scan.php?page=news_item&px=Schedutil-Freq-Invariance-V5

[polarathene]

The Linux kernel patches in their current form enable frequency invariance support for Intel Skylake X CPUs as well as Xeon Phi, Atom, and Atom Goldmont parts.

So the consumer focused core i3/5/7/9 lines are unable to benefit? Do they lack something that Atom and Skylake X have? Curious if a phoronix article is done in future if mainstream CPUs(including AMD) are affected in anyway by it when using schedutil? Is it using some CPU specific instructions/feature that the others lack?(or can it be enabled for others somehow?)

[aufkrawall]

So when will the kernel devs force schedutil for newer Intel CPUs, as they refuse AMD's governor?

[numacross]

So the consumer focused core i3/5/7/9 lines are unable to benefit? Do they lack something that Atom and Skylake X have?

I don't think so. The patch notes for v4 have benchmarks of Haswell, Broadwell and Skylake so I'd assume the consumer variants work as well.

Michael the link in the article is to v4 and not v5

[Slartifartblast]

Well I suppose it offsets some of the performance degradations thanks to mitigations, a rare scrap of good Intel news.

[timofonic]

It's nice to see improvements.

What about Schedutil vs Userspace?


What's the reason of the extremely wide variety of CPU governors in the Android community? Can there be a reason? How to solve it? Maybe CPU governors need to be heavily improved on Linux?

[skeevy420]

It's nice to see improvements.

What about Schedutil vs Userspace?


What's the reason of the extremely wide variety of CPU governors in the Android community? Can there be a reason? How to solve it? Maybe CPU governors need to be heavily improved on Linux?

On Android, the reason for so many governors is they tie in Android stuff to the governors like tap the screen and it'll ramp up or force it to stay on its lowest freq if the screen is off and stuff like that. Some of them do some interesting things and are pretty neat; though most of them are unnecessary and are just some random person's fun project to learn C and kernel development.

I'd reckon that none of them are worth using in regards to desktop users....some of them may benefit laptop & tablet users since most Android governors are designed around trying to balance saving battery life and overall performance.

[timofonic]

On Android, the reason for so many governors is they tie in Android stuff to the governors like tap the screen and it'll ramp up or force it to stay on its lowest freq if the screen is off and stuff like that. Some of them do some interesting things and are pretty neat; though most of them are unnecessary and are just some random person's fun project to learn C and kernel development.

I'd reckon that none of them are worth using in regards to desktop users....some of them may benefit laptop & tablet users since most Android governors are designed around trying to balance saving battery life and overall performance.

Then some of them have interesting features, your initial statement is wrong.

I think CPU governors need a lot more configurability. What about eBPF for other tasks other than network filtering?

[skeevy420]

Then some of them have interesting features, your initial statement is wrong.

I think CPU governors need a lot more configurability. What about eBPF for other tasks other than network filtering?

Tying into Android features can't be neat and interesting? What are you trying to get at?

I'm not saying that governors don't need more configurability, but I don't see how touchscreen frequency ramps and other such Android governor features help Linux desktop and server users; and I did say they'd be useful for Linux laptop and tablet users...Linux on a battery people.

The problem with more and more configurability is the governor gets to a point where it spends more time running checks and balances to decide what to do than actually doing it.

What's better, IMHO, are userspace tools, like Feral's GameMode, that are designed around specific tasks and can set the governor and frequency as necessary. Someone like myself might not need or want the governor to ramp up or down based on network-specific tasks and someone needing network based load monitoring might not want or need GPU load and mouse movement detection.

[milkylainen]

Well I suppose it offsets some of the performance degradations thanks to mitigations, a rare scrap of good Intel news.

Especially since "Intel Inside" has become "Intel waste heat Inside"