Ryzen 9 Support
entropie
Status: New User - Welcome
Joined: 31 Jul 2019
Posts: 3
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Hey there,

first of all thanks for the great liquorix kernel, I am using it for a couple of months now and I am pretty happy with it.
Now my question: I just updated to a Ryzen 9 3900X and its running perfect on the latest kernel. Yet those R9s still have issues to reach their max advertized boost clock, which is prolly related to their BIOS Agesa versions still needing optimisations. I am currently looking into that matter and want to learn more about it and was wondering, if there are Zen2 specific optimisations in the liquorix kernel or if there are any options I can try out.

I have made some single core benchmarks, where I let a Fast Fourier Transformation run contained to every of the 24 logical cores and the result is:

Highest I get is 4,44 Ghz on Core 13, I tested all of them:
https://openbenchmarking.org/result/1907307-HV-SINGLECOR71

On Core 0 the average fps are highest with 4,23 Ghz:
https://openbenchmarking.org/result/1907306-HV-DSFDS326725

Obviously the Ryzen architecture has different clock speeds on their cores, Core 0 and 13 are the two logical ones, which are the physical Core 0. At 4,44 ghz I am almost at 4,6 Ghz but not quite there yet.

Since I barely now stuff about the workings of liquorix just tell me if my question is nonsense or if you have any ideas and hints on this, I'ld like to know. I havent tweaked anything in the BIOS yet, just running on stock, only the RAM is at 3200 Mhz.

Thank you for your time,
Greetings ~ent
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damentz
Status: Assistant
Joined: 09 Sep 2008
Posts: 769
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Hi entropie,

In general, it'll be more difficult for you to hit the peak max boost clock on your CPU that's only attainable on single cores. This is because MuQSS more aggressively utilizes idle cores even when a single task is running, so it'll bounce between cores that share cache quite often. Task bouncing isn't particularly a problem unique to MuQSS, but the mainline scheduler CFS is better at pinning single threaded busy tasks to the same core it was running, so you should get a higher score if you stick with your distribution's stock kernel.

However, don't confuse benchmark scores with responsiveness. Liquorix typically scores worse in most synthetic benchmarks due to its higher context switching rate and usage of MuQSS. The trade-off is a system that feels better and more responsive for workstation type usage where you have lots of things running. I understand that's not what we're measuring here so lets move on to the actual boosting capabilities of the new Ryzen CPUs.

Toms Hardware released an article[1] discussing turbo boosting on Ryzen 3000 and found that not all cores are equal. In fact, the updated driver in Windows 10 is designed to understand which cores are the fastest and use those for single thread boosting whenever possible. As of now, both MuQSS and CFS understand general CPU topology by cache distance, but not by core quality. There's other efforts from Qualcomm to understand big.LITTLE architectures that are already used on android phones, which is similar but not the same.

And the only work I'm aware of to aggressively take advantage of single core turbo speeds are patches[2] developed by IBM to pack unimportant jitter tasks on to already active cores. But it's pretty clear from reading the abstract (to me at least), that this would be horrible for interactive usage like processing mouse cursor movements, desktop compositing, Xorg responding to input. All those things you want to respond as fast as possible, so running them all in parallel to get their time slice executed as soon as possible is more desirable, rather than as fast as possible but late.

[1] www.tomshardware.com/reviews/amd-ryzen-3000-turbo-boost-frequency-analysis,6253.html - Our Tests Show Not All Ryzen 3000 Cores Are Created Equal
[2] lkml.org/lkml/2019/7/25/296 - [RFC v4 0/8] TurboSched: A scheduler for sustaining Turbo Frequencies for longer durations
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entropie
Status: New User - Welcome
Joined: 31 Jul 2019
Posts: 3
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Hi damentz,

thank you that was very intresting, learnt a thing or three about the inner workings.

In the meantime, I did some testing on the 3900X myself and I got it to 4,524 Ghz. I achieved that speed by putting a nop-loop on and I had to film it via smartphone, cause otherwise I hadnt it gotten there. I suppose if there was no OS and no background tasks running, it would hit the 4,6 Ghz. Only on core 0 tho, what is thread 0 and 12.

Have a look here: https://www.youtube.com/watch?v=IDhriFlZjwo

I have finished this chapter of testing for me no, convienently accepting the fact that AMDs PBO pushes this CPU to the limit. I wont be wondering if they limit those CPUs standard BIOS settings in the future with upcoming Agesa versions, cause it seems to be pretty maxed out. The single core speed aint that important, cause besides that it is a monster. Running dxvk, wine, the actual game, h.264 encoding for streaming and recording and doesnt even sweat.

I have one last question left: would it be possible to get those patches in the liquorix kernel for Ryzen 3000 series temperature output? I am still only reading my mainboard temperature output on the CPU? This is the patch I think:

https://patchwork.kernel.org/patch/11043277/

Thank you and keep up the good work :),
~ent
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damentz
Status: Assistant
Joined: 09 Sep 2008
Posts: 769
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Just merged the patches from your link to zen-kernel's 5.2/master, but I'm already in the middle of building the next release. Your patches will be in the release after 5.2.0-10.3/5.2-15.
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entropie
Status: New User - Welcome
Joined: 31 Jul 2019
Posts: 3
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k10temp is working now, thank you ! :)
Now my conky is whole again :).

That CPU is a monster, already idling around 45 - 50 °C, yet under moderate load it only scales up till 60 °C, so stock Wraith prism absolutely suffices.

I am still stuck to 4,524 Ghz and the youtuber der8auer made a survey now on other peoples experiences in combination with their boards and Agesa versions. Its safe to say that obviously the problem is on the AMD side. They announced an Agesa update for 10th of September now, probably a reaction to the video, then we will finally see, if its software related or a manufacturing error. I am not sure yet, if I will update my BIOS with it, probably not. I am fine with my CPU and if it can reach only 4,524 Ghz by design I am ok with it, rather than overvolting it completly.

Thanks again for your help :)
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