Comment by user5994461
5 hours ago
> I wonder whether the next bottleneck becomes software scheduling rather than silicon
Yep, the scheduling has been a problem for a while. There was an amazing article few years ago about how the Linux kernel was accidentally hardcoded to 8 cores, you can probably google and find it.
IMO the most interesting problem right now is the cache, you get a cache miss every time a task is moving core. Problem, with thousands of threads switching between hundreds of cores every few milliseconds, we're dangerously approaching the point where all the time is spent trashing and reloading the CPU cache.
I searched for "Linux kernel limited to 8 cores" and found this
https://news.ycombinator.com/item?id=38260935
> This article is clickbait and in no way has the kernel been hardcoded to a maximum of 8 cores.
That's the one. Funny thing, it's not actually clickbait.
The bug made it to the kernel mailing list where some Intel people looked into it and confirmed there is a bug. There is a problem where is the kernel allocation logic was capped to 8 cores, which leaves a few percent of performance off the table as the number of cores increase and the allocation is less and less optimal.
It's classic tragedy of the commons. CPU have got so complicated, there may only be a handful of people in the world who could work and comprehend a bug like this.