Excellent links!
Brainlet wrote: ↑09 Dec 2020, 20:31
And of course, it might also just be placebo but you will never find out without eliminating bigger latency bottlenecks beforehand.
Also, occasionally in situations where it is hard, sometimes a slight amount of latency to add smoothing becomes necessary -- people who use things like RTSS Scanline Sync to get perfect frame pacing, slightly more lag than VSYNC OFF but lots less lag than VSYNC ON.
Such tradeoff decisions in optimization are now continually being made. Also, for example, in virtual reality where you might need, say, 1ms of better movement-processing in order to better perfect 1:1 vertigo sync between real life motions and virtual motions. Sometimes engineers are confronted with a decision between "1ms tape-delayed-but-perfect vertigo sync" versus "0ms-delayed jittery motion that is dizzying/nauseous" from the VR movement sensors, etc. Such tough compromises occur when displays become bigger, more realistic, and more immersive (or even strapped to a face).
We believe in letting users decide how to optimize (latency priority, smoothness priority, compromises, etc), since sometimes they are opposing optimization goals for certain settings.
<Future Talk>
Also, the discussion about the potential
High Definition Mouse API now recommends sensor-side timestamping, as a workaround to avoid pollrate overheads from eating up CPU cores (e.g. 8KHz-20KHz sensorreads embedded into 2KHz poll rate).
Basically, with the theoretical HD Mouse API for future game software (which 2 mouse vendors now liked after I emailed them about it), it is possible to have a software application receiving 20,000 timestamped sensor reads per second at only 2000Hz poll rate. That's still technically lower lag than 1000Hz, consumes less CPU than 8000Hz mouse poll rate, while giving more mouse deltas to software than an 8000Hz poll rate, so an acceptable smoothness-vs-latency balance with both concurrently still improving. Or purists can sensor-and-poll match, if they wish.
One still get latency reductions relative to, say, 1000Hz mouse, even if not latency reductions all the way down to 1/8000sec-1/20000sec. That said, the API is flexible on the tradeoff on latency-prioritization and temporal-resolution prioritization (by giving up some of the further latency decreases).
The different use cases of smoothness-vs-latency is delicate. Esports competition prioritizes on the latency aspect, while reality-emulation (maximum motion quality) on perfect smooth 1:1 stutterfree sync with real life (whether emulating reality on a screen, TV, monitor or VR). The latency-versus-smoothness tradeoff hits lots more brick walls as we get closer and closer to retina refresh rates, and some divergences can become necessary in some use cases.
</Future Talk>
Though the above API talk is not always relevant in today's tweaking -- smoothness-vs-latency tradeoffs is already becoming a tougher optimizing job with ever higher frame rates at ever higher refresh rates.
For readers --
Know what priorities you are optimizing for (latency priority, smoothness priority), since a few percent of settings you're tweaking (e.g. 5% or 10% of them) may change, like how HPET-like settings makes certain software better and other software worse, etc.