AlderLake anyone?

[scan80269]

George, I can assist with Alder Lake testing also.

One thing to keep in mind regarding Intel Alder Lake is that this processor family should run Windows 11 instead of Windows 10. Win11 has scheduler optimizations that work in conjunction with the Intel Thread Director feature of Alder Lake for improved performance. Win10 scheduler has no hybrid core architecture support and does not differentiate between the P and E cores of Alder Lake.

[JWNoctis]

Originally Posted by mackerel

A possible explanation I've seen is that both cores need to share a common feature set. As threads get moved around you can't end up with a situation where code needs AVX-512, but it can't be provided by the E cores. The solution for now is to disable AVX-512 where you have E cores present. Unfortunately they have also said you can't get AVX-512 back by disable E cores and run only P cores. I had hoped something smarter could be done at OS level, where for example code needing AVX-512 would only be run on P cores and not touch the E cores at all.

For consumer level CPUs, for bigger FFTs were way into the region where ram bandwidth is limiting. In that scenario, the loss of AVX-512 is less of an impact, and having faster DDR5 speeds would probably result in a net increase to performance.

Where the loss of AVX-512 will be felt more is for those like me who focus on smaller FFTs that are not limited by ram speeds. The open question remains, just what sort of FMA performance can the E cores provide? It might be a case of quantity over quality to provide a possible net positive in performance.

Admittedly, my first reaction was wondering if that is some sort of market segmentation, before realizing just now that the segmentation's been there since the beginning, by limiting memory bandwidth.

...Which is too slow, considering that I've already seen my computer hitting that limit, where there's only <5% performance gain of large-FFT throughput for 30% more clock frequency, 50% more power consumption, and running 20 degrees Celsius hotter, even without AVX-512, before I tuned it down a bit.

Another thing worth looking out for might be large L3 cache and very large and exotic L4 cache, though I doubt either would be coming to anything justifiably affordable to most individuals anytime soon from any manufacturer.

[Skatterbencher]

What would be the appropriate version for Prime95 to use with ADL-S and Win11?


If any further help is needed, I can also assist.

[Prime95]

Originally Posted by Skatterbencher

What would be the appropriate version for Prime95 to use with ADL-S and Win11?

Any version should work but may need some tweaking. Prime95 cannot handle some cores with hyperthreading and some without. To run a torture test you'll need to look in undoc.txt for NumCPUs and CPUHyperthreads. If Alderlake is 2 hyperthreaded performance cores and 3 non-hyperthreaded efficiency cores then set NumCPUs=7 and CPUhyperthreads=1.

Similarly, prime95 will struggle assigning workers to the performance cores. Start and cancel a benchmark. Look at results.bench.txt. You'll likely need to tell prime95 which core(s) to assign to each worker. See Affinity= in undoc.txt.

[Skatterbencher]

Thanks!

[Prime95]

Version 30.7 available:

https://www.mersenneforum.org/showthread.php?t=27180

The one user that has tried this had problems. I need more data to hopefully figure out what is going on.

[tuckerkao]

Originally Posted by Prime95

Does anyone here have access to an Alder Lake system?

I thought Intel 12900k won't be available until Nov 4, 2021, has it been released early?

What DDR5 memories does 12900k support? How expensive are those?

[Prime95]

Originally Posted by tuckerkao

I thought Intel 12900k won't be available until Nov 4, 2021, has it been released early?

I don't know the release date. Those who have one are under a non-disclosure agreement. They cannot tell you anything about what it supports or does not support.

[Batalov]

Newegg and other retailers started taking preorders...
Tempting!

[Prime95]

Originally Posted by Batalov

Newegg and other retailers started taking preorders...
Tempting!

Disclaimer: I know absolutely nothing about AlderLake's performance.

If it were me, the way Intel has fallen behind AMD over the last 5 years, I would wait until some hard numbers came out.

[JWNoctis]

In other news, apparently Intel had lifted the default PL1 setting for at least the higher-end Alder Lake processors and motherboards...to 241W.

Smells gamey, with a hint of toasted electronics - Wonder what would Prime95 and similar workloads do to the processor and its VRM, with power limits like that? Not that whatever happens would not probably be covered by warranty with default setting like that, and not that Prime95 doesn't already have disclaimers for such damage in its EULA, though.