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Comment by HelixEndeavor | Hacker News Reader

So presumably a bug that can be fixed by either AMD updating their optimizer, Factorio updating to work better with it, or both?

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If it's a problem for Factorio it's also a problem for others, so definitely something to fix on the AMD side.

Its more of a fundamental scheduling issue. The unlike big/little cores OS has no idea what apps "prefer" cache or frequency.

An OS can easily run an app on each for a few milliseconds, look at the performance counters to see which ends up with more instructions executed, and then move the task to where it performs best.

From time to time, it can retry the test, because software frequently changes what it spends time doing.

But apps like factorio are extremely dynamic, so thats either going to be flakey or its going to spend a lot of time/energy bouncing the process between cores.

I wouldn't be too worried about this personally, as configuring the few really sensitive apps with ProcessLasso or Aniancy is pretty easy.

I feel that with good statistics this could be done in the OS scheduler successfully. But it’s not my area of expertise.

I don't think the average Factorio gamer is going to know that they should do this or how. They will just know that their new CPU which was supposed to have better gaming performance is doing very, very poorly.

You are talking about Factorio players who specifically bought an 3D-L3 CPU, I would guess awareness would pretty high, personally...

> You are talking about Factorio players who specifically bought an 3D-L3 CPU

Factorio players don't necessarily know anything about computers. And you don't know if they bought this CPU or if it came with their fancy prebuilt.

I'm pretty sure this is how Nvidia's game ready drivers work. They come with a bunch of pre-made profiles for popular video games, so the optimal settings are configured based on what applications are being executed, which is also why you have to let it scan for your games, so it knows what executables to watch for, so it can properly select the right profile to use.

And that's why we have the "Game Ready" driver mess.

My understanding is there's a certain amount of nvidia cleaning up after the game developers too. e.g. replacing poor performing shaders with optimised versions or just old-MS style "let's change how the driver works to keep the game working". Which is why they've been so resistant to opening the driver, they believe some of their perf advantage/secret sauce is in the driver rather than the hardware.

Affinity in the O/S?

A properties page for the executable with a checkbox for “favour stacked cache cores” or some such.

Factorio is infamous for being radically memory bandwidth limited. Which yes is a problem others will have... but not many in gaming afaik.

Given the primary selling point of these CPUs vs their non-X3D version is having more cache for memory access heavy workloads, if this is not a problem for your workload you're likely not in a position to gain much from the X3D variant anyway.

Or just buy the X3D that have cache on each CCD instead of half of them.

More precisely, buy the X3D that has only one CCD.

There is currently no consumer model with 2 CCDs and X3D on both of them.

Right, so the 7800X3D (due in April), the old 5800X3D, or any future threadripper or Epycs with the X3D.

Best L3 per core outside of the X3Ds it the 7600 or or 7900 CPUs that come with the full size L3 (32mb PER ccd) but only 6 cores per CCD (instead of 8).

Can't you disable the CCD without the 3D cache? I remember being able to disable 3 CCDs on my Threadripper using Ryzen Master for gaming.

Yeah... if you're going to see bigger gains from the cache, fewer cores in 7800X3D in early April is probably a better option (same for gamers).

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