[LU-13005] Remove LNet event queuing subsystem (lib-eq)

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.14.0
• Assignee: Neil Brown
• Reporter: Neil Brown

Description

lib-eq provides a "event queue' which allows one thread to add events to a queue, and another to remove them, or wait for more.

Such a  queue would be useful if LNet were accessed from user-space: allowing user-space to pluck events of a queue with minimal interaction with the kernel would be valuable.  But lnet/eq is never used like that.

Almost all users for LNet/eq allocate a queue with zero slots and provide a call-back to be called for each event.  This is a sensible approach when producer and consumer are in the same address space (i.e. both in the kernel).

The one exception is lnet_ping() which allocated a 2-element queue.  lnet_ping() can easily be re-written to use a call-back, with a reduction in code size.

So let's remove the whole EQ subsystem and just use callbacks everywhere.

 

Issue Links

• is related to: LU-14810 sanity-lnet test_212: lnet_assert_handler_unused() ASSERTION(md->md_handler != handler) failed
• is related to: LU-12678 LNet simplification work from linux client