AMD + Valve Working On New Linux CPU Performance Scaling Design

[phoronix]

Phoronix: AMD + Valve Working On New Linux CPU Performance Scaling Design

Along with other optimizations to benefit the Steam Deck, AMD and Valve have been jointly working on CPU frequency/power scaling improvements to enhance the Steam Play gaming experience on modern AMD platforms running Linux...

https://www.phoronix.com/scan.php?pa...e-New-CPU-Freq

[intelfx]

About time.

So, once again something only happens in Linux when there is a commercial interest. Not before, not after.

[aufkrawall]

Just to be fair: schedutil or intel_pstate powersave are bad too vs. Windows balanced profile.

[perpetually high]

This is really exciting. I'm not on the new AMD chips, but eventually I will be.

I'll use the analogy by the creator of the CFS-enhanced with ULE scheduler (CacULE):

"in short, if we imagine that the Linux kernel is a car, then the Completely Fair Scheduler (CFS) is the engine, CacULE is a hack on throttle system (to make the engine more responsive), and RDB is a turbo."

Scheduler is very important and unless this kind of collaborative effort is happening, we won't see the real performance gains we should be seeing.


EDIT: And on a side note in regards to the GPU scheduler, back when I was mining ethereum on my Polaris GPU, I could mine with Polaris and use my computer and not even know it was doing it.

When I had temporarily switched to the GTX 1080, that was no longer true. The desktop/OS lagged and lagged, was super sluggish. I'm pretty sure it was the GPU scheduler and nVidia had an inferior one than AMD on Linux, and absolutely no one can tell me different because the machine was exactly the same, just GPU swapped out, and all the necessary "were the right drivers/settings configured?"

Point being, if they can get the CPU scheduler down, AMD will have great performance on the CPU and GPU scheduling sides. Of course, I am not an expert or professional, so take everything i'm saying with a slight grain of salt.

[perpetually high]

About time.

So, once again something only happens in Linux when there is a commercial interest. Not before, not after.

You say that like it's a woke statement. More of a captain obvious

Hey, linux is free, and anyone can modify it. You want to gain traction and movement, yeah, you're going have to put money, people, and resources behind it. Who has those? Commercial interest and corporations. So what exactly is your point?

[skeevy420]

Cool. I hope this'll help my Zen 2 APU...preferably with my 580 because that's my gaming setup.

Not Sure if having Vega or RDNA2, iGPU or dGPU, or DDR4 or 5 matters here. This is one of those Phoronix articles that links back to other Phoronix articles and not to an external source.

[MadCatX]

Just to be fair: schedutil or intel_pstate powersave are bad too vs. Windows balanced profile.

Are they? The last round of benchmarks showed that schedutil has closed the gap on performance and performs just as well in most workloads. Unless the Windows' balanced performs better than Linux' performance, I wouldn't call schedutil bad.

Hopefully this collaborative effort will lead to improvements to the schedulers that we already have instead of something specific for gaming workloads and Zen chips. Anyway, it's awesome to hear that this is finally getting attention.

[david-nk]

When I had temporarily switched to the GTX 1080, that was no longer true. The desktop/OS lagged and lagged, was super sluggish. I'm pretty sure it was the GPU scheduler and nVidia had an inferior one than AMD on Linux, and absolutely no one can tell me different because the machine was exactly the same, just GPU swapped out, and all the necessary "were the right drivers/settings configured?"

This was my experience as well, I had to switch to a RTX GPU because ROCm just wasn't there yet, but the Nvidia scheduling and memory management is really bad. Firefox went to updating the screen with less than 1 fps (disabling GPU acceleration helps though) and the rest of the desktop also feels sluggish. The memory allocator also has trouble allocating larger chunks of VRAM when there still should be enough memory left. As a result, there are some networks that I can only train with a batch size of 3 when I trained them with a batch size of 8 on my previous Polaris GPU (both cards have 8 GB VRAM). I also noticed when an Nvidia GPU is under load, a fullscreen XPutImage/XShmPutImage takes about 1 second to complete instead of the normal 1 ms. That seems to be part of the problem.

But CPU frequency scheduling remains a problem. Even old Linux veterans are surprised by how much faster a project sometimes compiles when switching to the performance governor. All workloads with frequent sleeps or I/O pauses (compiling, games, video playback) are a nightmare to the current schedulers.

[V1tol]

I am considering buying Steam Deck (of course if/when it arrives to my hole) just to sponsor AMD and Valve on their Linux efforts. I hope when many AMD+Radeon machines will be on Linux with top performance, maybe Intel will start improving their scheduler to benefit my notebook (i funded Intel) and maybe Novideo will opensource their driver (i funded them too). Just stupid dreams here

[aufkrawall]

Are they? The last round of benchmarks showed that schedutil has closed the gap on performance and performs just as well in most workloads. Unless the Windows' balanced performs better than Linux' performance, I wouldn't call schedutil bad.

avg fps and even 1% low percentile don't show bad influence on frame time variance well enough. You will see MangoHUD's frame time graph to look bad with schedutil/powersave when under certain load conditions, causing stutter, missed vblanks etc. While schedutil is way better than intel_pstate powersave (why is this crap the default setting...), it is still not good enough.