Workqueue (Screenplay)

Add Workqueue

• Clearly per-device

• device.{h,c}

  • wq member

  • Use create_workqueue(), destroy_workqueue()

# ps -efl|grep my_driver
# ps -eo pid,cmd,rtprio,nice

Talk about realtime a bit.

Submit/Defer Work From Atomic Context

• device.{h,c}: add struct work_struct right next to wq

• Dummy work function (printk())

• INIT_WORK() in device ctor

• Submit from atomic

  • Interrupt

  • Timer callback

• Check if called

# chrt -p 20 <pid>

Cleanup (Why We Did This, After All)

• Remove gfp_t parameter from my_event_list_add()

Finish

• Interrupts at high rate (e.g. from a bouncing switch) ⟶ some are dropped

• We did this to get rid of the spinlock

  • ⟶ re-introduce mutex