[dagmx]

Generally HT/SMT has never been favored for high utilization needs or low wattage needs.

On the high utilization end, stuff like offline rendering or even some realtime games, would have significant performance degradation when HT/SMT are enabled. It was incredibly noticeable when I worked in film.

And on the low wattage end, it ends up causing more overhead versus just dumping the jobs on an E core.

[The_Colonel]

> And on the low wattage end, it ends up causing more overhead versus just dumping the jobs on an E core.

For most of the HT's existence there weren't any E cores which conflicts with your "never" in the first sentence.

[dagmx]

It doesn’t because a lot of low wattage silicon doesn’t support HT/SMT anyway.

The difference is that now low wattage doesn’t have to mean low performance, and getting back that performance is better suited to E cores than introducing HT.

[The_Colonel]

> It doesn’t

Saying "no" doesn't magically remove your contradiction. E cores didn't exist in laptop/PC/server CPUs before 2022 and using HT was a decent way to increase capacity to handle many (e.g. IO) threads without expensive context switches. I'm not saying E cores are a bad solution, but somehow you're trying to erase historical context of HT (or more likely just sloppy writing which you don't want to admit).

[dagmx]

I’ve explained what I meant. You’ve interjected your own interpretation of my comment and then gotten huffy about it.

We could politely discuss it or you can continue being rude by making accusations of sloppy writing and denials.

[The_Colonel]

No, you haven't explained the contradiction, you just talk over it. Before E cores were a thing, HT was a decent approach to cheaply support more low utilization threads.

[jeffbee]

Backend-bound workloads that amount to hours of endless multiplication are not that common. For workloads that are just grab-bags of hundreds of unrelated tasks on a machine, which describes the entire "cloud" thing and most internal crud at every company, HT significantly increases the apparent capacity of the machine.