On Wed, 22 Jun 2022 06:40:20 -0700, Dylan Yudaken wrote:
> Task work currently uses a spin lock to guard task_list and
> task_running. Some use cases such as networking can trigger task_work_add
> from multiple threads all at once, which suffers from contention here.
>
> This can be changed to use a lockless list which seems to have better
> performance. Running the micro benchmark in [1] I see 20% improvment in
> multithreaded task work add. It required removing the priority tw list
> optimisation, however it isn't clear how important that optimisation is.
> Additionally it has fairly easy to break semantics.
>
> [...]
Applied, thanks!
[1/8] io_uring: remove priority tw list optimisation
commit: bb35381ea1b3980704809f1c13d7831989a9bc97
[2/8] io_uring: remove __io_req_task_work_add
commit: fbfa4521091037bdfe499501d4c7ed175592ccd4
[3/8] io_uring: lockless task list
commit: f032372c18b0730f551b8fa0a354ce2e84cfcbb7
[4/8] io_uring: introduce llist helpers
commit: c0808632a83a7c607a987154372e705353acf4f2
[5/8] io_uring: batch task_work
commit: 7afb384a25b0ed597defad431dcc83b5f509c98e
[6/8] io_uring: move io_uring_get_opcode out of TP_printk
commit: 1da6baa4e4c290cebafec3341dbf3cbca21081b7
[7/8] io_uring: add trace event for running task work
commit: d34b8ba25f0c3503f8766bd595c6d28e01cbbd54
[8/8] io_uring: trace task_work_run
commit: e57a6f13bec58afe717894ce7fb7e6061c3fc2f4
Best regards,
--
Jens Axboe
