From: Thomas Gleixner <t...@linutronix.de> Sent: Wednesday, November 7, 2018 12:23 PM > > There is another interesting property of managed interrupts vs. CPU > hotplug. When the last CPU in the affinity mask goes offline, then the core > code shuts down the interrupt and the device driver and related layers > exclude the associated device queue from I/O. The same applies for CPUs > which are not online when the device is initialized, i.e. if non of the > CPUs is online then the interrupt is not started and the I/O queue stays > disabled. > > When the first CPU in the mask comes online (again), then the interrupt is > reenabled and the device driver and related layers reenable I/O on the > associated device queue. >
Thanks! The transition into and out of the situation when none of the CPUs in the affinity mask are online is what I wasn't aware of. With that piece of the puzzle, it all makes sense. Michael
