Due to the nature of recent and current CPUs and their cores, it would be wonderful to be able to assign a hierarchy to the CPU Affinities and CPU Sets, instead of the hierarchy assigned by default.
To try to achieve a better understanding of the issue, I'd like to illustrate and specify the above using my particular case:
As you may know or as can be confirmed in Ryzen Master, since the Ryzen 3000 series AMD (I'm fairly certain AMD assigns this at the factory, though I'm not completely sure whether Windows or the motherboard are involved, in any case, I'll refer to it as "Windows'" or "stock" from here on) assigns a hierarchy to the cores based on their stock electrical characteristics, prioritizing the two "best" cores.
Well, in my case, after tuning my CPU (a 5600X), whether by undervolting the stock configuration or by overclocking and undervolting it, via PBO and monitoring it, it turns out that the stock hierarchy is almost reversed when compared to the electrical hierarchy under those several different modifications. Even worse, its two preferred cores (the "best" ones) are electrically and therefore thermally the worst. Specifically, the order of the cores in my CPU is the following (without signs: normal core numbering; in parentheses: stock hierarchy; in brackets: observed electrical hierarchy):
1 (3) [4]
2 (5) [3]
3 (1) [6]
4 (4) [1]
5 (6) [2]
6 (2) [5]
As you can see, my two "best" Windows cores are inversely my worst electrically. And the difference between the "best" and "worst" is significant, for example: in a given application (a game), my "best" factory core reaches 4.85 GHz at 1.419 V, whereas my best electrically core after tuning reaches the same frequency at 1.335 V, and therefore with lower temperature. This wouldn't be a major issue if it weren't for the fact that I've observed that within its algorithms the 5600X imposes a thermal limit for a given frequency, the limit for that one (4.85 GHz, the CPU's maximum) being 65°C. It's not unusual for the preferred cores to exceed that temperature, which makes the tuning useless under such scenarios.
As is known, the core hierarchy cannot be changed (only can be disabled), but fortunately there's Process Lasso. Thanks to its documentation and practical use, I've found that the best way to replicate Windows' behavior while assigning the electrically best cores and avoiding the worst ones is through CPU Sets. However, unfortunately it has a small flaw: it still obeys Windows' hierarchy.
In my case, to replicate the original behavior I need to assign 3 cores (the third one is barely used). The best ones in numerical order are 4, 5, and 2, however, their hierarchy in Windows is 4, 6 and 5, respectively. So, since CPU Sets follow the Windows hierarchy and this doesn't match the electrical one, the result is a less-than-optimal thermal outcome. Fortunately, in my case my best core is hierarchically ahead of the other two, but surely there must be cases where the final electrical and thermal result from CPU Sets or Affinities would be not good or even the worst possible one.
I suppose this only affects processes that use few cores, like games, and I know this is a bit tangled and perhaps a picky issue, but it would be good if it could be addressed.
In summary, given the nature of recent and current CPUs (at least Ryzen) and the arbitrariness of Windows' hierarchy, it would be beneficial if Process Lasso could assign its own hierarchy to CPU Sets (and by extension to Affinities), overriding the Windows' one. Is this possible?
Thank you in advance for taking the time to address my question.
That's interesting!
It stands to reason that the pre-marked "best" cores may no longer be the actual top performers after certain CPU configuration changes, such as overclocking.
We'll have to research whether it is possible to change the best cores list the OS uses. We have already planned to mark those cores, so we'll do that research at the same time. If there is a way, we'll find it ;).
I'll update this thread with any developments.
Really thoughtful breakdown of the issue—CPU behavior gets surprisingly nuanced at this level, and it's the kind of deep optimization mindset I usually only see when people are really into things
Yep, overriding it for CPU Sets could indeed unlock better thermal and frequency efficiency.