[gruez]

This will cause the system to vastly under-report % values during periods of low load, because the processor thinks it can run at a higher frequency than it can actually achieve/sustain. This is most notable on laptop processors. If I enable "high performance" mode on windows, it would cause the processor to run at its max possible frequency, around 4.1 GHz (which is near the theoretical max turbo frequency) when there's little to no load. However, when there's actual load (eg. 1 core fully loaded), the frequency would drop to around 3.5 GHz. It would get worse as more cores get loaded, all dropping all the way down to 2.3ghz.

[dataflow]

What problem would this cause to me as a user, though? It sounds fine to me.

[gruez]

At 5% load, you might think there's 95% capacity to spare, but really it's actually something closer to 65%.

[dataflow]

3.5 GHz instead of 4.1 GHz is a 15% difference, not 30%. I never expect multicore performance to be the same as single-core so if that's what you're assuming, it's an unreal assumption. I expect lower clock speeds for multicore regardless of what Task Manager shows.

But okay, so there's some discrepancy, whether 15% or 30%. Okay, so I might underestimate it, and... then what? What would actually go wrong?

I think what you're not realizing is that underestimating capacity is a very different situation from overestimating it (especially when we're talking about underestimating like 0.4 GHz vs. 4 GHz, as opposed to overestimating 2-3 GHz as 4 GHz). When I'm looking at CPU usages it's almost always to figure out who's overutilizing the CPU, not underutilizing it. If I underestimate utilization, then at worst, what happens is I launch a program that needs all cores for max throughput (say a video encoder?), and then get disappointed at its throughput being too small. This is so infrequent (if it happens at all for the average user) that the additional mental effort required to factor in the throttling is quite negligible, and the negative consequences are quite mild. Compare that to the case where I overestimate utilization: suddenly I semi-panic and try to kill the program using the most CPU, and boom, suddenly I'm at risk of losing a bunch of data. The difference is quite asymmetric.

[Godel_unicode]

It sounds like you don't ever engage in capacity planning. You should read about it, real usage numbers are very important.

[dataflow]

It sounds like you don't ever use a computer as a consumer. Go ask your non-technical friends how often they're "capacity planning" when they pull up Task Manager.

And I'm just talking about what 99% of ordinary users expect most of the time. Nothing prevents you from measuring whatever metrics you want either. Obviously "I think this is what most people expect utilization to mean" obviously does not imply "I think you should be banned from anything else you might find useful"...

[Godel_unicode]

You've never heard someone say "my CPU is running hot all the time, I need to upgrade"?