Things are finally coming together :D
In 2018, I think it will be possible to build a small and cost efficient steam machine with lots of games.
This will be possible thanks to AMD DC being mainlined and the now great performance of radeonsi + radv, on the software side.
On the hardware side, the Ryzen+Vega+HBM2 gaming APU should be very interesting if it turns out to be true: https://www.pcgamesn.com/amd-ryzen-mobile-gaming [External Link]

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Quoting: GuestI'll try to explain PTHREAD_SCOPE better...

Thanks for the very comprehensive answer! <3

Quoting: berillionsSo ...
I would like to buy a Ryzen 5 1400 but with this problem, the good deal is :
- To buy this Processor even with this issue for this game and maybe in future games. Even if a fix exist
- To buy an Intel Processor ...

There are a lot of problem with Ryzen processor on Linux; i don't know what i must to do ... Intel or AMD processor ...

I did a quick run of benchmarks to simulate the performance of a 4C and 6C Ryzen cpus by restricting the cores the game has access to.
Keep in mind it's only a simulation so a real 4C/6C Ryzen cpu could behave differently.

First Shadow of Mordor:

4C/6C performance is lower than 8C (to be honest I was expecting 6C performance to be similar to 8C so it's a surprise here) while the worst by far is with default scheduling.
All in all the performance hit with a 4C is significant but not something that would make the game unplayable.

Now Hitman:

This is quite different from Shadow of Mordor:
- the default scheduling is fine and the CCXes don't seem to create any problem
- there is very little difference between 4C, 6C and 8C. And the benchmark is mostly cpu bound.

I personally think what you see with Hitman will be closer to the average experience you'll get with a 4C Ryzen cpu. But I would need to do a lot more benchmarks to confirm this.
Don't forget also that more and more titles will use Vulkan which will reduce the cpu overhead so things should get better too.

On the flip side, please note the Ryzen 1400 has half the level 3 cache of all other Ryzen cpus (8MB vs 16MB) so this could adversely affect performance.

If you don't want to have to bother with all these things, you might indeed be better off with an intel cpu, though intel has no competition at the R5 1400 price (Core i3 are useless now that there is the pentium G4560). But with a Ryzen cpu, you have a very good upgrade path down the road, just by changing the cpu alone.

Honestly, I think there are four possibilities:
- you're on a tight budget: get the pentium G4560 and a good GPU. Try to grab a second hand 7700 / 7700k in a couple of years.
- you have a medium budget: get the Ryzen R5 1600 and overclock it. You will be able to upgrade to more cores / better single thread performance down the road (Ryzen 2)
- you have a high budget and want the best performance now: get a 7700k and overclock it
- you have a high budget and want some future proofing: get a Ryzen 7 1700 and overclock it

If you opt for a Ryzen cpu, make sure to get good DDR4 (at least 2666Mhz, single rank if you can get that information).

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Quoting: SamsaiThis is a fantastic piece of research right here. Mad respect for the guest writer!

Thanks a lot, it's much appreciated ^_^

Quoting: soulsourceThe right place to "fix" this issue is the task scheduler of the OS, and I would be strongly surprised if we wouldn't see patches from AMD that address such issues soon.

Quoting: shirethroneVery interesting read. I like to have background information.
Do developers have to act or the kernel to fix this issue?

In this case, I don't know for sure.

IIRC the linux kernel was patched by AMD in version 4.9 so it should be aware of Ryzen's topology and schedule threads accordingly. And indeed, the scheduling is working fine generally.

At some point I even tried to do all sorts of manual scheduling with Dirt3 on Wine and each single time the result was slightly to much worse than letting the scheduler do its job.
That's why I was surprised to see this performance hit with Shadow of Mordor. At this point I pretty much expected manual scheduling to be useless.

So it may be a problem with the game forcing scheduling in a manner that doesn't work well with Ryzen but we would need a confirmation from Feral to be sure.

Quoting: pete910To stop the stuttering maybe better fixing it to the real cores not the firs 8 or so
[...]
Better for me using
taskset -c 0,3,5,7,9,11,13,15 %command%

I just did a quick test where I scheduled the game only on even logical cores (so at most one thread per real core) and I obtained a similar result as with the default scheduling. So it seems that it is indeed an issue with the CCXes and not SMT. This would make sense as I have no such issue on the i7 2700k.

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Quoting: GuestWhen I was doing Linux development at VP, one of the things we determined was that Linux REALLY needs to implement PTHREAD_SCOPE_PROCESS to allow games to better prioritize how their threads get scheduled, for just reasons like this. They quite often do on Windows, and this carried along correctly on OS X, but Linux only has PTHREAD_SCOPE_SYSTEM which effectively makes it impossible for a process to prioritize its own threads well.

This is really interesting, first time I hear about this.
Could you give more information on the difference between PTHREAD_SCOPE_PROCESS and PTHREAD_SCOPE_SYSTEM? I've read the manual but still don't clearly understand what difference it makes in practice.

On this specific issue, I thought the solution would be more to separate each CCX as different NUMA nodes so the scheduler could take into account the additional cost of having interdependent threads on different CCXes?

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Quoting: cip91skThanks for the heads up! However I remember reading that the infinity fabric's speed is dependent on RAM frequency, and that at ~3200+ mhz games weren't affected so much, so can you tell us what configuration are you using? And, if possible, can you try again at higher RAM frequency?

I use DDR4 @ 2400 Mhz CL12.
Unfortunately I can't test with higher speeds for now as 2666Mhz results in a boot loop and I need to remove the BIOS battery / clear CMOS to get the computer to boot again.
This is probably because I have dual rank memory that isn't playing well with Ryzen for now (bought it real cheap last summer when we didn't know Ryzen would be that picky with RAM).

I expect the new bios updates in June to improve things (especially with the ability to choose 2T command rate) so I'll test again if I can get the memory higher.

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Quoting: Leopard

Quoting: drmothCan't wait. And Windows has only DirectX11 support, no DX12. This is a first! Go Feral!!

The reason is DirectX 11 is still performing good and OpenGL was so behind of it at performance terms

I'm happy that Feral is adopting Vulkan more and more.

Deus Ex Md and Hitman are also needs to be Vulkanized

Exactly, it seems DirectX 11 lends itself to multithreading a lot better then OpenGL, though not as ideally as Vulkan.
I'd also like to see some Vulkanized Hitman, this game is so severely CPU bottlenecked, it's detracting from the otherwise awesome experience.

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Great news, I think we could use more arcade racing games on Linux.
Will definitely buy it if it's good.

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Quoting: Whitewolfe80

Quoting: ghemAwesome news <3
I sense an AMD APU based Steam Machine in a not so distant future :woot:

Aww thats cute you think Steam machines are still a thing

People fail to realize that Valve is in for the long term (I know, not a popular notion these days with shareholders impatient to get their 300% ROI in 6 months).
People also fail to realize Steam machines are not only there to protect Valve's market against microsoft, it's equally a tool to grab market share from consoles.

And no Steam Machines are not dead.
Valve did launch them because it was be the only way to actually work out in the open and to generate an initial interest so as to get things going.
Currently, they're doing all the required, laborious work on the ecosystem: removing roadblocks (AMD drivers), improving the experience (Steam controller, BPM), pushing Vulkan.
Though they still are lagging severely behind in the video department (Netflix, Youtube, etc.)

Only when the ecosystem is ready will it be the time for a big push.
Tough I don't really have a clue as to how to do that.
Release a standard, officially endorsed Steam Machine?
Release a new Valve game with a temporary SteamOS / Linux exclusivity? (I know they don't like exclusive games, but who knows)

They pushed Steam by making it a requirement for Half-Life but they can't do the same with SteamOS because it would be too intrusive for the user. So I wonder how they would entice people to switch, how they would differentiate themselves in the eyes of the average consumer.
What could you do on a Steam machine that you wouldn't be able to on a windows PC or a console? Or that you would be able to do in a better or different way?
So far, I only see the Steam controller, but I wonder if that's enough

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Awesome news <3
I sense an AMD APU based Steam Machine in a not so distant future :woot:

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