[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

Comments

[Peter Jones]

It looks like all existing patches have landed - is there any further patches still to come?

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/38059/
Subject: LU-13005 lnet: Support checking for MD leaks.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: b7278ecc699b5bd7c431222c93f1f209f02d4670

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/37378/
Subject: LU-13005 lnet: remove 'eq' from names, use 'handler'
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: ff8a305376bf8833011ec81d4c3fe750d15597a8

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36847/
Subject: LU-13005 lnet: remove lib-eq.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 0cf2b328fe1a417e3c4d5ff6216e0b86738d28bf

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36846/
Subject: LU-13005 lnet: drop refcounting from event queues.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: c927c62f93feb66aa440c43e1b85ceb86863c01a

[Gerrit Updater]

Neil Brown ([e-mail]) uploaded a new patch: https://review.whamcloud.com/38059
Subject: LU-13005 lnet: Support checking for MD leaks.
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 05e9231729c93c376e4965cb32496793c7d5ea3a

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36845/
Subject: LU-13005 ptlrpc: use percpu refcount to track requests.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: bee5cd85a8e35b8dbf0e16e9a380812f74d4f422

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36844/
Subject: LU-13005 lnet: remove the 'queue' from LNetEQ
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: d277f2ae95d0d0580059561706face3accfe3618

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36843/
Subject: LU-13005 lnet: remove LNetEQPoll
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 570cd57fe62d8ba820a51604b956fb1003fdff06

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36842/
Subject: LU-13005 lnet: don't use LNetEQPoll for ping replies.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 952109670beb638b70e71212b177e8b2a73b6910