If you're wondering about that one from few weeks ago. One person from Intel noticed the article and confirmed the kernel bug, they ran some of the kernel benchmarks on their 24 core CPU and found up to 15% improvements when fixed (most difference on scheduler fifo benchmark, though 0% difference on most benchmarks).
I've ran the same on my computer at home and I also got double digit percent difference on a 32 cores AMD.
I thought the basic premise was wrong that the Kernel only uses a maximum of 8 cores. It was rather some scheduling logic that was implemented with a maximum of 8 cores in mind. So the author may have been right that something was wrong, but also wrong about the details (like in this article)
https://news.ycombinator.com/item?id=38260935