Linux Games/Apps Might Get Greater Control Over GPU Frequency On Intel Hardware

[phoronix]

Phoronix: Linux Games/Apps Might Get Greater Control Over GPU Frequency On Intel Hardware

Chris Wilson of Intel's Linux graphics driver team posted a big set of 36 patches on Wednesday for their DRM kernel driver...

http://www.phoronix.com/scan.php?page=news_item&px=Intel-Per-App-GPU-Freq-Control

[eydee]

If a game can say "hey, I want high performance mode", it's good. If a game can say "hey, I want 4798.5 MHz", that's very bad.

[Guest]

I feel it's stupid. I mean, the whole point of kernel vs userspace is to make sure that only the kernel controls the hardware. Any application should NOT have to specify GPU frequencies to get good performance, that's just crappy software development practice. Requesting a high performance or low performance GPU profile makes sense. Actual frequency specification should NEVER be an option (even if kernel will perform checks and only allow safe values).

[boxie]

This is rather interesting - I would say they would have to be very careful in controlling the power/cooling budget in the driver - but user space being able to give workload hints to the driver is the main take away here, I like it

[M@yeulC]

I feel it's stupid. I mean, the whole point of kernel vs userspace is to make sure that only the kernel controls the hardware. Any application should NOT have to specify GPU frequencies to get good performance, that's just crappy software development practice. Requesting a high performance or low performance GPU profile makes sense. Actual frequency specification should NEVER be an option (even if kernel will perform checks and only allow safe values).

Well, to me it sounds relatively sane, for fine-grained control over performance. You would need some kind of arbitrarily normalized value otherwise, so I feel that going with the frequency is sound.

Just keep it mind that it seems to be intended for adjustment based on previous experience (say, clock lower and lower until you drop a frame, and use this as a baseline for future operations, croteam for example does a mini benchmark in serious Sam 3 to set performance settings).

[audir8]

I guess if the app/game looked at my battery life, and decided it could give me 15 more minutes of battery life by running at minimum settings and lower frequency, and did it all transparently with maybe a friendly prompt... that would be great. I think apps/games can already check battery life and act accordingly, they just don't bother to do anything different most of the time..

[Guest]

......all of that is the domain of the GPU driver. Any application that uses 3D graphics APIs shouldn't also be worrying about how to conserve battery life. It's not the game's job in any way, to control GPU frequency or worry about it.

At best, request a lower or higher performance profile.

[cl333r]

Doesn't Vulkan leverage these needs?

[audir8]

......all of that is the domain of the GPU driver. Any application that uses 3D graphics APIs shouldn't also be worrying about how to conserve battery life. It's not the game's job in any way, to control GPU frequency or worry about it.

At best, request a lower or higher performance profile.

I don't know too much about game design, but I think a game could cap FPS at 60, and estimate (maybe with a couple tries) which frequency would let it accomplish that goal best. It would be different for Civ 6 vs Tomb Raider. Asking for a low/high profile is doing the same thing, why not just let it be more fine grained? You're the game dev, you should know how much memory bw and gpu processing you need. You can actually do all of what I'm saying currently by making application profiles in the Nvidia driver. How many games actually bother? None that I've seen. Instead I'm the one who has to worry about overheating or battery power, and downclock the gpu myself. All of it being done automatically by the app is definitely a need I've had as a user.

This is all expecting quite a bit from game devs, and you might be right, but I can only hope apps will be more performance aware especially in scenarios with a battery. Perhaps a higher level vendor agnostic API that exposes simpler controls for devs might do the trick.