Linus Torvalds (torvalds.delete@this.linux-foundation.org) on December 30, 2020 12:00 pm wrote:
> Foo_ (foo.delete@this.nomail.com) on December 30, 2020 2:50 am wrote:
> >
> > Also it is probably not wise to feed more than 16 high-performance cores using
> > only two channels of memory.
>
> For a lot of loads, the L3 caches in the chiplets would probably make it work quite
> well. Yes, you'd get memory-bound, but it might still be worth it to get the extra
> cores depending on what you do. Caches do work. I think most of what I do would be
> perfectly fine with just two channels and the kinds of caches the 5000 series has.
>
> I suspect the bigger issue is power delivery and cooling. I think most AM4 processors are specced to 105W
> TDP (with peak power delivery being another 40% or whatever). Threadrippers are what, 280W TDP?
>
> Yes, if you want to do overclocking, you'll get a AM4 board and heatsink that can do more than the
> specced power delivery, and maybe it would work fine to push it. But the difference between TDP specs
> on AM4 and Threadripper is quite noticeable, and I'd expect that to be a more immediate issue.
>
> Linus


For me, the ecological aspect is also important. I prefer to favor a "green" CPU with high energy efficiency rather than a CPU which is an energy vampire difficult to cool... Yes Threadrippers are at 280W of TDP vs 105 Watts of TDP for the Ryzen 9 5950X.

The other thing that bothers me with the Threadrippers is that they seem to be equivalent to the Xeons from Intel, i.e. CPU's mostly oriented high-end workstation and servers, with a lot of L3 cache, which I do not need. And then there is also a certain price difference also between Rysen and Threadrippers processors family...

For the moment I have ordered a Rysen 5950x AM4 to replace my aging i7-5960x, an X570 motherboard with fanless chipset and 32 Gb of Ram low latency @ 3200 Mhz. Everything costs me +/- 1600 US $, approximately the price of one Threadripper 3960X. I will be able to keep my old cooling system, my power supply and my old case and resell my old components for cheap :) And as you say I will be able to gain 30% of computing power by overclocking it if necessary without taking any risk of damaging my hardware.

I take this opportunity to thank you 1000 times for having developed support for this hardware under Linux so quickly via the 5.10.x kernel. Debian is currently my favorite Linux OS, I think the Backports directory will be offering this new kernel in just a few days :)

If you allow me to notice, on the page kernel.org/category/releases.html it is stated that an update time for the LTS 5.10.x kernel will only last until December 2022. Although you are changing certainly this end of support date at the end of 2022, like you did for kernel 4.19, I think such information may confuse some people and create negative publicity for Linux. By showing such a short lifespan for an LTS kernel, some people may think that it would be a bad choice to adopt it, as it will lead to kernel update complications !! And this 5.10.x kernel will be the official kernel for Debian 11. If things stay that way on this website, it can clearly create a counter-advertisement for Debian 11 ;-(

I dare to hope that my dream of a 24 or 32 core AM4 CPU will come true and that I could upgrade my CPU afterwards while keeping my X570 motherboard and its memory. Time will tell us...

Happy new year 2021 to all with a few hours in advance and thank you again to those who gave me a better perception of things thanks to the discussions we had above :)

Philippe