AP adapter interrupts

Linux® instances that run in environments with support for AP adapter interrupts use such interrupts to indicate the completion of cryptographic requests. These environments include Linux in LPAR mode, in a DPM partition, and guests of all hypervisors that support AP adapter interrupts.

Using AP interrupts instead of the polling thread frees one processor while cryptographic requests are processed. The polling thread is deprecated and used only in hypervisor environments where AP adapter interrupts are not available.

To query whether AP adapter interrupts are used for your Linux instance, read the sysfs interrupt attribute of the device. Another interrupt attribute at the AP bus level, /sys/bus/ap/ap_interrupt, indicates that the AP bus is able to handle interrupts.