Why does an ultrabook need a 4-core processor?

Question

laptops

I have two identical laptops, they differ only in that one has a 2-core Core i5-7300U processor, and the other has a 4-core Core i7-8650U. And you know what? The real difference in speed between them is noticeable only when comparing head-to-head, and it is very scanty, and in some tasks 2 cores are faster. Meanwhile, there are more problems with the 4th core than with the 2nd (I will describe which ones at the end).

Now I have turned off turbo boost on 4 cores, and I'm trying to find a task that will need 8 threads. Clearly, there is gaming there, heavy scientific calculations, but I didn’t take a business ultrabook for these purposes. LibrOffice and similar software 1-2 streams. Video from yottuba is hardware decoded. The best parallel I've found is browsing, but even here, when the video is spinning in one tab and I'm actively loading pages in others, I couldn't load 8 streams by more than 60%. More often, I see something like 35% in the peak for some kind of action.

35% of 8 threads is only 3 threads - they don't need more than 3 cores. But even a rare 60% is only 5 threads, since they are rare, then a 3-core 6-thread processor is enough for them.

As a result, it appears that 3 cores 6 threads is exactly what you need. Why produce 4 cores in a processor with a base TDP = 15 watts on a 14nm process technology ??

And now, 4 cores are worse than 3:
1. The complexity of SpeedStep and SpeedShift only grows with the increase in the number of cores. A dual-core processor achieves maximum turbo boost at full load even at EPP=160, while a quad-core processor needs to reduce it to about EPP=110, and this means large frequency reserves and, as a result, lower efficiency.
2. Less base frequency affects some tasks. So a 2-core with base 2.6 boots 2 seconds faster than a 4-core with base 1.9. I note that the laptops are the same, except that in a 4-core ssd one and a half times faster (although nvme is there and there).
3. Cost of production

I would really prefer a 3-core 6-thread processor with a base frequency of 2.3 GHz than 4 core 8 threads with a base frequency of 1.9, not only because of the base, but because of the possibility of setting an EPP of about 130 to get both the maximum turbo boost and not such a large frequency reservation.

But no .. 4 cores ... to maintain adequate frequencies in light and medium loads, you have to set EPP to 127, and get a maximum frequency of 3.5 GHz, instead

of 4.2 In new business ultrabooks, processors with 6-8 cores and 12-16 threads . What for??

Answer 1

Ultrabook, 4-core processor, 8 threads. And this is not enough for me! I use it mainly for software development. A couple of threads are consumed by the development environment. A couple more - the programming environment. A couple more - the database. A couple more - a browser with a hundred tabs. And I also want a virtual, or even a couple, and music and a movie in the background. Well, there would be a couple of free ones under the graph editor ...
And yes, gigahertz is not important - streams are our everything!