Windows 11 Is Changing How Task Manager Calculates CPU Utilization
With Insider Preview build 26120.3360, Windows is making a change to how Task Manager reports CPU utilization. What change? Well, Microsoft says it "will now use the standard metrics to display CPU workload consistently across all pages and aligning with industry standards and third-party tools." In other words, it's going to attempt to measure the actual utilization of your CPU cores at their current clock rate.
Don't worry; if you need access to the original metric (say, for comparing data against old sources), you can still access it under the "CPU utility" column. It will be disabled by default, though, and you'll have to go poking around in the Task Manager settings to enable it. You also won't be able to use it on the main CPU utilization page, but rather only in the 'Details' view.
So wait, what was it doing before? Historically, Windows has based its performance metrics against the reported base clock speed of your CPU. This was fine back in the Windows 2000 days, when computer clock speeds did not normally change after boot. These days, computers spend very little time at their "base" frequency, as they turbo above it for higher performance and then clock far below the base frequency for power savings.
Image from Brendan Gregg's excellent blog post, "CPU Utilization is Wrong."
Of course, we could have a broader discussion about how the entire metric of "utilization" is highly misleading because of the time that cores spend waiting on I/O or stuck in spin locks, but that's an entire other conversation. This is still a solid step forward for Microsoft's long-lived tool, and we're happy to see the company making positive changes, however small, to Windows amidst a sea of not so great 24H2 news.
