I think we have a problem with link bandwidth change notifications (see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/bw_notification.c). Here's a recent bug report where Jan reported "_tons_" of these notifications on an nvme device: https://bugzilla.kernel.org/show_bug.cgi?id=206197 There was similar discussion involving GPU drivers at https://lore.kernel.org/r/20190429185611.121751-2-helgaas@xxxxxxxxxx The current solution is the CONFIG_PCIE_BW config option, which disables the messages completely. That option defaults to "off" (no messages), but even so, I think it's a little problematic. Users are not really in a position to figure out whether it's safe to enable. All they can do is experiment and see whether it works with their current mix of devices and drivers. I don't think it's currently useful for distros because it's a compile-time switch, and distros cannot predict what system configs will be used, so I don't think they can enable it. Does anybody have proposals for making it smarter about distinguishing real problems from intentional power management, or maybe interfaces drivers could use to tell us when we should ignore bandwidth changes? Bjorn
