[wtallis]

When the OS has asked the CPU to slow down to more closely match the performance currently required by the software, then it is somewhat misleading to report that an application is using 90+% of the CPU time, even if the CPU is actually spending 90+% of its time running that application.

However, when the CPU's speed has been reduced because it's too hot or the system is otherwise unable to allow the processor to sustain its full clock speed, you absolutely should see the Task Manager reporting 100% utilization. This scenario is what more often comes to mind when the term "throttled" is used.

If a hardware platform's power management capabilities make it impractical for the operating system to satisfy both of the above goals, then it should favor the latter goal, and err on the side of not lying to the user when your system is truly operating at its limits.

[taneq]

> However, when the CPU's speed has been reduced because it's too hot …

Maybe just measure overall system load as current CPU temperature as a percentage of maximum?

[wtallis]

That's a decent method for some purposes, though it's not without its own flaws. For systems using integrated graphics or any laptop, the CPU's thermals are intertwined with the GPU's. You may also have a workload that sends a CPU core to its highest stable clock speed and safe voltage, but is still cooled well enough that the CPU doesn't get close to its temperature limits. Or you could have a situation where the CPU can tolerate a higher temperature, but it has to throttle so as not to burn the user because a fair chunk of that heat is being conducted up through the keyboard and down into the lap.

[MauranKilom]

> but it has to throttle so as not to burn the user because a fair chunk of that heat is being conducted up through the keyboard and down into the lap.

I've never used a mobile device that seemed to have such considerations. They all seem perfectly happy to make their surface scalding hot. Do manufacturers actually care about this?

[PeterisP]

Perhaps in stable environments that would be reasonable, but it would also mean that if I put my laptop in the sun, the system load should become large and potentially (hot heatwave sun on a dark laptop) exceed 100% even if the laptop is completely idle.