Re: Support for more than 256 CPU cores

On 5/5/23 17:23, Tomek CEDRO wrote:
> On Fri, May 5, 2023 at 3:38 PM Ed Maste wrote:
>> FreeBSD supports up to 256 CPU cores in the default kernel configuration
>> (on Tier-1 architectures).  Systems with more than 256 cores are
>> available now, and will become increasingly common over FreeBSD 14’s
>> lifetime. (..)
> 
> Congratulations! :-)
> 
> I am looking after AMD Threadripper with 64 cores 2 threads each that
> will give 128 CPU to the system.. maybe this year I could afford that
> beast then I will report back after testing :-)
> 
> In upcoming years variations of RISC-V will provide unheard before
> number of CPU in a single SoC (i.e. 1000 CPU) at amazing power
> efficiency and I saw reports of prototype with 3 x SoC of this kind on
> a single board :-)
> 
> https://spectrum.ieee.org/risc-v-ai
> 

Hi,

Maybe it makes sense to cluster CPU's in logical groups somehow. Some 
synchronization mechanism like EPOCH() are O(N²) where N is the number 
of CPUs. Not in the read-case, but in the synchronize case. It depends a 
bit though. Currently EPOCH() is executed every kern.hz .

--HPS