Threadripper 1920x handbrake encode is faster with SMT off

[MtKingsnake]

Hello. Playing with my 1920x I have have found a quirk, that I am not sure how to or if to proceed as if there is a problem.

I ran some hand brake tests. With SMT on and off. Here is the data in seconds. Each trial was replicated 3 times
All core 3700mhz smt on: 131, 129, 132
All core 3700mhz smt off: 108, 108, 111
All core 3800mhz smt off: 107, 106, 106

Is this a handbrake problem? or an SMT problem, or something else? I would have thought that smt on would at least perform as well as off, but not significantly worse. Not 20% slower.

Thanks for any ideas or thoughts on the situation.

[Log]

Certain workloads actually benefit from disabling core threads (the opposite can also be true), for reasons I don’t really understand and am not qualified to talk about.

What you saw seems normal if this is to be trusted

A Look at AMD's Threadripper CPU Hardware Modes

Even some games can see benifits

Does Disabling SMT on a Ryzen 7 CPU Improves its Performance? - Page 6 of 7 -...

[MtKingsnake]

Huh. OK, cool. Glad to see it isn’t just my chip.

[MtKingsnake]

The good news is that with SMT off, the encodes go faster, and the chip runs cooler (and presumably uses less electricity. I need to get a meter one day).

[modzilla]

Are you using Windows for your tests?

[MtKingsnake]

Linux mint.

[SgtAwesomesauce]

Hmmm, I’d never seen this data, but since it seems like my workload might benefit from it, I might have to disable SMT to see how it works.

[MtKingsnake]

I would love to see if your workload also benefits.

[SgtAwesomesauce]

The workload I run that’s intensive is DaVinci Resolve and ffmpeg, so it’s quite similar.

[modzilla]

thx!