Re: PSA: Clock drift and pkgin

I believe you. But aren't we now getting into pretty realtime stuff? Not 
sure NetBSD is at all suitable for such applications/environments. As 
you say - if this only behaves acceptably if the system is not under 
load, then it's not a solution I would go for.

But again - I guess we're talking very personal 
opinions/experiences/tradeoffs here.

I still don't really believe we need very high resolution scheduling. 
And tickless is sortof a separate topic to this.

   Johnny

On 2023-12-31 05:20, Konrad Schroder wrote:
> On 12/30/2023 3:42 PM, Johnny Billquist wrote:
>> On 2023-12-31 00:11, Michael van Elst wrote:
>>> Better than 100Hz is possible and still precise. Something around 1000Hz
>>> is necessary for human interaction. Modern hardware could easily do 
>>> 100kHz.
>>
>> ? If I remember right, anything less than 200ms is immediate response 
>> for a human brain. Which means you can get away with much coarser than 
>> even 100Hz.
>> And there are certainly lots of examples of older computers with 
>> clocks running in the 10s of ms, where human interaction feels perfect.
> 
> I'm not sure about visual and auditory sensation, but haptic VR requires 
> position updates >= 1000Hz to get texture right.  The timing of two 
> impulses that close together may not be felt as two separate events, but 
> the frequency of vibrations within the skin when it interacts with a 
> surface (even through a tool, such as a stylus) is encoded by the nerve 
> endings in the skin itself.  We used to use PHANTOM haptic arms at 
> $WORK, driven by an Indigo2. If the control loop operated at less than 
> 1000Hz---for example, if the Indigo2 was under load--- it introduced 
> noticeable differences in the sensation of running the pen over a 
> virtual object.  The simulation was much more sensitive to that than it 
> was to the timing of the video output, for which anything greater than 
> 72Hz was wasted.
> 
> Take care,
> 
> -Konrad
> 

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: [email protected]             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol