linux-kernel - [PATCH liburing v2 0/1] test: add epoll test case

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Date:   Fri, 31 Jan 2020 15:29:42 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org
Subject: [PATCH liburing v2 0/1] test: add epoll test case

Hi Jens,
this is a v2 of the epoll test.

v1 -> v2:
    - if IORING_FEAT_NODROP is not available, avoid to overflow the CQ
    - add 2 new tests to test epoll with IORING_FEAT_NODROP
    - cleanups

There are 4 sub-tests:
    1. test_epoll
    2. test_epoll_sqpoll
    3. test_epoll_nodrop
    4. test_epoll_sqpoll_nodrop

In the first 2 tests, I try to avoid to queue more requests than we have room
for in the CQ ring. These work fine, I have no faults.

In the tests 3 and 4, if IORING_FEAT_NODROP is supported, I try to submit as
much as I can until I get a -EBUSY, but they often fail in this way:
the submitter manages to submit everything, the receiver receives all the
submitted bytes, but the cleaner loses completion events (I also tried to put a
timeout to epoll_wait() in the cleaner to be sure that it is not related to the
patch that I send some weeks ago, but the situation doesn't change, it's like
there is still overflow in the CQ).

Next week I'll try to investigate better which is the problem.

I hope my test make sense, otherwise let me know what is wrong.

Anyway, when I was exploring the library, I had a doubt:
- in the __io_uring_get_cqe() should we call sys_io_uring_enter() also if
  submit and wait_nr are zero, but IORING_SQ_NEED_WAKEUP is set in the
  sq.kflags?

Thanks,
Stefano

Stefano Garzarella (1):
  test: add epoll test case

 .gitignore    |   1 +
 test/Makefile |   5 +-
 test/epoll.c  | 386 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 390 insertions(+), 2 deletions(-)
 create mode 100644 test/epoll.c

-- 
2.24.1