Hi there, I’m running Fedora 42’s Wayland GNOME session with Linux kernel 6.14.2 on a ThinkPad T480 (Intel Core i5-8350U CPU), with only a single GPU (Intel Kabylake chipset) connected to two external monitors at 60 Hz, connected to AC power in the default “Balanced” power mode… and I’ve been puzzled by the tick_nohz_handler timer item consistently showing up in powertop at the top of things waking up the CPU, no matter what I do with the computer sitting idle:
I tested with all GNOME Shell extensions turned off, with no particular processes running (but even if I am running Firefox in this picture, it seems to not be waking up the CPU often in practice), etc.
On another computer with AMD CPU+GPU, with only a logged in GNOME Shell Wayland session with no apps running, I still see the tick happening, albeit less frequently than on my own computer:
I tried searching for this on the Interwebs, and other than the kernel’s documentation page about that (which I don’t really understand… and does Fedora enable that in its kernel anyway?), all I found are some occasional Reddit threads (like this one and that one) that ultimately end up nowhere, with no clear answer.
Anyone savvy about how the kernel or power saving features work in Fedora: what is going on, is it normal to be seeing so many wakeups (between 200 to 700 per second) from that thing? Is powertop just hallucinating things?